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15 November 2016, Volume 37 Issue 11 Previous Issue    Next Issue
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Information & Control

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Identification of Wind Tunnel System Using Multivariable Step Responses ZHANG Ting-feng， MAO Zhi-zhong， YUAN Ping， ZHANG Bi 2016, 37 (11):  1521-1525.  DOI: 10.12068/j.issn.1005-3026.2016.11.001 Abstract ( 787 )   HTML   PDF (747KB) ( 782 )   Because the 2.4m×2.4m wind tunnel is a multivariable-coupling system， the impact of a single control variable on the outputs cannot be obtain directly from the operating data. For this reason， the multivariable-coupling parametric model of the wind tunnel and filtering processing of the data with step response was proposed by the cubic spline interpolation method. The area method was applied to the parameter identification from the step response data of each channel， and the best model of each channel was determined by the root mean square error of different model orders. Wind tunnel experiments show the effectiveness of the proposed method. References | Related Articles | Metrics

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Method of Power Distribution Network Fault Diagnosis Based on Improved Time Fuzzy Petri Net LIU Xin-rui， GAO Yi-wei， WANG Zhi-liang 2016, 37 (11):  1526-1529.  DOI: 10.12068/j.issn.1005-3026.2016.11.002 Abstract ( 759 )   HTML   PDF (522KB) ( 718 )   In distribution network， the equipments in different regions have different reliabilities， and the automation of fault diagnosis is at low level. In order to make the fault diagnosis quick and accurate，a new method of distribution network fault diagnosis was presented based on improved time fuzzy Petri net. Firstly， the information of breakers with the switch and electrical information were corrected，and the areas where power collapse were found out. Then， according to the range that the breaker can protect， the suspicious fault elements were found out， and the time fuzzy Petri net model for suspicious fault elements with time-tag information was built.Finally the diagnosis results were given. The simulation results show that the efficiency and accuracy of fault diagnosis are improved. In addition， the fault process can be shown for dispatchers with good practical application value. References | Related Articles | Metrics

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Four Arm Mobile Working Robot Linkage Control for High Voltage Transmission Line Based on BP Neural Network JIANG Wei， WU Gong-ping， FAN Fei， ZHANG Jie 2016, 37 (11):  1530-1535.  DOI: 10.12068/j.issn.1005-3026.2016.11.003 Abstract ( 728 )   HTML   PDF (899KB) ( 1105 )   In response to the shortage of tension clamp drainage board bolt tighten for high voltage transmission line on artificial low operation efficiency， labor-intensive， high-altitude， and high risk， a four arm mobile working robot was designed. In order to improve the operation efficiency， a robot arm linkage control algorithm was proposed based on BP neural network. The linkage control of the robot was abstracted into trajectory tracking control problem. In the Matlab environment， robot manipulator end tracking simulations were carried out from three directions. Finally the robot charged tighten bolt was tested on the actual line. Simulation and field tests verified that the proposed four arms mobile work robot linkage control method is feasible and effective with a strong engineering practicality which meet the design requirements of improving the operation efficiency. References | Related Articles | Metrics

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Robust Finite-Time Energy-to-Peak Control for Systems with Discrete and Distributed Delays ZHENG Lian-wei 2016, 37 (11):  1536-1540.  DOI: 10.12068/j.issn.1005-3026.2016.11.004 Abstract ( 613 )   HTML   PDF (355KB) ( 1246 )   The robust finite-time control problem under the constraint of energy-to-peak performance index was investigated for linear systems with delays. Norm-bounded uncertainties was included in the coefficient matrices of systems and discrete and distributed delays were included in the states. A Lyapunov functional involving a parameter was introduced. Its exponential growth was checked for bounding the states and outputs. Then， sufficient conditions were derived guaranteeing that the closed-loop systems are finite-time bounded and satisfy prescribed energy-to-peak performance index for all admissible uncertainties. What’s more， the control law was obtained simultaneously. These conditions were formulated in terms of linear matrix inequalities with an eigenvalue constraint. Through transforming the constraint to nonlinear matrix inequalities， a cone complementarity linearization algorithm was designed to solve such matrix inequalities. An example was presented to show the effectiveness of the proposed method. References | Related Articles | Metrics

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QGrid: A Parallel Indexing Structure for Spatial Moving Objects LI Chuan-wen， CHE Qing-shou， GU Yu， DENG Qing-xu 2016, 37 (11):  1541-1546.  DOI: 10.12068/j.issn.1005-3026.2016.11.005 Abstract ( 656 )   HTML   PDF (495KB) ( 694 )   In order to improve updating efficiency and querying accuracy for spatial moving object data， a parallel indexing structure for spatial moving objects was proposed. A main index and an auxiliary index were contained in the proposed structure， which were used for supporting range based and identity based spatial object query operations， respectively. A query index was also utilized which hooks updating operations to querying operations that may be influenced. Thus locking relevent spatial objects and indexing structures could be avoided when range query operations are processed. At the same time， it also support timeslice semantics for parallel operations. Experimental results show that， under high working load， the structure can not only guarantee querying accuracy， the throughput is also obviously higher than that of the existing methods. The index improves the degree of system parallelism， makes it possible for object updating and querying operations in same ranges be processed in parallel， and therefore improves the overall efficiency of the system. References | Related Articles | Metrics

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An Uncertain Spatiotemporal Data Model Based on XML BAI Lu-yi， XU Chang-ming， LIU Xu-long， YU Chang-yong 2016, 37 (11):  1546-1550.  DOI: 10.12068/j.issn.1005-3026.2016.11.006 Abstract ( 692 )   HTML   PDF (512KB) ( 696 )   Uncertainty in spatiotemporal data is common and inevitable because of data distortion， data loss， or network delay. Accordingly， an approach that can process spatiotemporal data without being affected should be proposed. XML makes it powerful to model， represent， and manage uncertain spatiotemporal data. Data in traditional relational database is based on relations. When representing temporal attributes， it can generate a large amount of data redundancy. Therefore， it cannot represent uncertain spatiotemporal data in relational database effectively. The uncertain spatiotemporal data model was proposed to improve the ability of data representation， which was consist of classifying different kinds of XML nodes and introducing probability attributes to represent uncertain spatiotemporal XML nodes. References | Related Articles | Metrics

Materials & Metallurgy

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Effect of Ni Content on Microstructure and Hardness of Laser Cladding Layers SUN You-zheng， LIU Shuai， LI Jin-bao， LIU Chang-sheng 2016, 37 (11):  1551-1554.  DOI: 10.12068/j.issn.1005-3026.2016.11.007 Abstract ( 808 )   HTML   PDF (722KB) ( 714 )   To fulfill the demand of surface hardness of remanufacturing various backup rolls， iron based alloy powder mixed with pure nickel powder were cladded on the surface of Cr5 backup steel by laser. The effect of Ni content on microstructure and properties was investigated. The results showed that the microstructure in all laser cladding layers was fishbone-like and net-like dendrites. The alloy composition of the cladding layers could be accurately controlled by the amount of pure nickel powder. With increasing nickel content， the austenite phase in the layer significantly increased， whereas the hardness of the layer drastically decreased. Wear resistance of cladding layer was better than traditional quenching work layer with similar hardness. The hardness of the cladding layer from the powder mixed with 8% pure nickel powder was about 500 HV， which could fulfill the demand of remanufacturing Cr5 backup rolls. References | Related Articles | Metrics

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Study on Wrinkle Defect in Square Box of Tailor Rolled Blank ZHANG Hua-wei， WU Jia-lu， LIU Xiang-hua， WANG Xin-gang 2016, 37 (11):  1554-1558.  DOI: 10.12068/j.issn.1005-3026.2016.11.008 Abstract ( 707 )   HTML   PDF (1155KB) ( 721 )   The wrinkle defect in the square box of tailor rolled blank (TRB) was studied by numerical simulation and stamping experiment. The mechanism of producing such wrinkle defect in TRB square box was analyzed and the effect of the binder force on the wrinkle defect was discussed. The results indicate that the spots inclined to form the wrinkle in the TRB square box are the straight flange on the thinner side and the flange in the thickness transition zone. When the binder force on the thicker side is not great enough， the wrinkle could also form at the straight flange on the thicker side. Under the conditions of no crack and the large movement in the thickness transition zone， the larger binder force can help to improve the wrinkle resistance of TRB and when the binder force is constant the restriction of the wrinkle of TRB is the best. References | Related Articles | Metrics

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Numerical Simulation and Optimization of Gas-Solid Heat Transfer Process in Sinter Vertical Tank FENG Jun-sheng， DONG Hui， GAO Jian-ye， LI Han-zhu 2016, 37 (11):  1559-1563.  DOI: 10.12068/j.issn.1005-3026.2016.11.009 Abstract ( 678 )   HTML   PDF (483KB) ( 795 )   Taking 360m2 sintering machine with the annual output of 3900kt sinter in an iron and steel company as a research sample， a mathematical model of gas-solid heat transfer process in sinter vertical tank was established. The main factors affecting the gas-solid heat transfer process in vertical tank and their influence rules were studied through numerical simulation and the suitable operation parameters was determined. The results show that with the decrease of gas superficial velocity and the increase of air inlet temperature， the sinter outlet temperature gradually increases， as well as the outlet temperature of cooling air. The decrease of sinter particle diameter results in the decrease of sinter outlet temperature and the increase of air outlet temperature. The optimal operation parameters of vertical tank are as follows: the air inlet flow under the standard condition is 455000m3/h， the particle equivalent diameter is 0.025m and the air inlet temperature is 130℃. References | Related Articles | Metrics

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Effect of Multiple Factors on Droplets During Electroslag Remelting Process DONG Yan-wu， CHEN Hao-yu， LI Xiang， WU Zhen-xiang 2016, 37 (11):  1564-1569.  DOI: 10.12068/j.issn.1005-3026.2016.11.010 Abstract ( 665 )   HTML   PDF (1645KB) ( 799 )   Magnet-hydr-dynamics (MHD) module loading current and voltage coupled with a VOF (volume of fluid) model for the phases (i.e.， steel and slag) distribution have been employed to investigate the formation of droplet during electroslag remelting. The results indicate that the amount of droplets increase with the increasing of filling ratio and the dimension of droplets increase with the increasing of electrode tip angle and interfacial tension. However， the amount and dimension of droplets decrease with the increasing of input current. Some large droplets could be tore into pieces by various forces including electromagnetic force， gravity， buoyancy and so on. In addition， multiple unsymmetrical eddies exist due to stochastic droplet dripping and uneven thermal field distribution. References | Related Articles | Metrics

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Simulation and Analysis of Chemical Looping Oxygen Production System Based on Aspen Plus YU Qing-bo， REN Hui-lai， PENG Jia-yan， WANG Kun 2016, 37 (11):  1569-1572.  DOI: 10.12068/j.issn.1005-3026.2016.11.011 Abstract ( 738 )   HTML   PDF (588KB) ( 864 )   The chemical looping oxygen production system was designed based on thermal analysis and pressure analysis .Then Aspen Plus chemical process simulation software is used to simulate and analyze the influence of reactor temperature and pressure on system energy consumption in order to optimize the oxygen production system. The results show that under ordinary pressure with the increasing of oxygen reactor temperature the system energy consumption decreases; whereas with the increasing of oxidation reactor temperature the energy consumption increases; and also the smaller the difference of temperature between two reactors is， the lower the system energy consumption is. Under negative pressure with the decreasing of the pressure of oxygen reactor， the system energy consumption decreases. However， under positive pressure with the increasing of the pressure of oxidation reactor， the energy consumption first decreases and then increases. Therefore， the optimization of operating parameters can be obtained in the oxygen production system where oxygen reactor runs under negative pressure and oxidation reactor under positive pressure. References | Related Articles | Metrics

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Water-Water Ejecting Behavior in a Natural Circulation Evaporation Cooling System FENG Ming-jie， WANG En-gang， FENG Hui-cong 2016, 37 (11):  1573-1577.  DOI: 10.12068/j.issn.1005-3026.2016.11.012 Abstract ( 571 )   HTML   PDF (670KB) ( 680 )   The ejecting behavior of a new ejecting technique， named water-water ejecting technique， which is used to start up the natural circulation evaporation cooling system for a reheating furnace is numerically simulated with Fluent 6.3 software.The influences of ejecting tube diameter， diameter ratio of outlet to inlet and ejecting flowrate on circulating velocity and local resistance loss coefficient of the evaporation cooling circuit nearby ejecting tube are studied. The results indicated that the flow characteristics of water in the cooling circuit follows the general law of confined isothermal jet ejecting. The circulating velocity increases with the increasing of ejecting flowrate， but it decreases with the increasing of diameter ratio of outlet to inlet when the ejecting tube diameter is constant. At the same time， the circulating velocity decreases with the increasing of ejecting tube diameter when the ejecting flowrate and diameter ratio of outlet to inlet are both constant. The performance of necking-type ejecting tube is better than that of flared-type considering the ejecting performance and resistance loss. References | Related Articles | Metrics

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Synthesis and Electrochemical Properties of Cathode Materials Na(Ni0.5Mn0.5)O2 for Na Ion Batteries LIU Guo-qiang， LI Yue， DU Yu-long 2016, 37 (11):  1578-1581.  DOI: 10.12068/j.issn.1005-3026.2016.11.013 Abstract ( 680 )   HTML   PDF (1246KB) ( 752 )   Layered structure Na(Ni0.5Mn0.5)O2 oxide was synthesized using CH3COONa， Ni(CH3COO)2·4H2O and Mn (CH3COO)2·4H2O as starting materials after dissolution， drying and calcining. The crystal structure， morphology of the prepared sample was investigated by XRD and SEM. There was small amount of NiO phase in the product， and the product is of layered structure. Their particles were less than 5μm and there was particle aggregation. The charge-discharge testes for the samples were also carried out. The prepared sample exhibited good rate capability. It delivered a capacity of 124，121，116.7，110.6 and 73.8mA·h/g at 0.1，0.2，0.5，1 and 5 rate，respectively. After 30 cycles， its capacity retention ratio was 94.8% at 25℃ and 91.1% at 55℃. It can be used as cathode material for sodium ion batteries. References | Related Articles | Metrics

Resources & Civil Engineering

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Flotation Behavior of Hemimorphite and Smithsonite in Dodecylamine System HAN Cong， WEI De-zhou， SHEN Yan-bai， LIU Wen-gang 2016, 37 (11):  1582-1587.  DOI: 10.12068/j.issn.1005-3026.2016.11.014 Abstract ( 710 )   HTML   PDF (692KB) ( 858 )   Monomineral flotation tests have been carried out for investigating the flotability of hemimorphite and smithsonite in dodecylamine (DDA) system. Flotation test results show that flotability of hemimorphite is higher than smithsonite， both of them have the best flotability in the range of pH 10～11. Solution chemistry calculation and zeta potential measurement results show that DDA adsorbs on hemimorphite and smithsonite surface mainly through the electrostatic interaction， and the association reactions between DDA molecular and DDA cationic can enhance the collecting capacity. Zeta potential measurement， X-ray photoelectron spectroscopy (XPS) detection and solution chemistry calculation results show that the point of zero charge (PZC) of hemimorphite is less than that of smithsonite. The first-principles calculations and contact angle measurement results show that hemimorphite is more hydrophobic than smithsonite. References | Related Articles | Metrics

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Removal Mechanism of Lead (II) Ions by Bioflocculant MBFA9 from Aqueous Solution JIANG Bin-hui， LI Feng-da， LIU Qian， HU Xiao-min 2016, 37 (11):  1588-1592.  DOI: 10.12068/j.issn.1005-3026.2016.11.015 Abstract ( 482 )   HTML   PDF (674KB) ( 630 )   The bioflocculant produced by a stain of Paenibacillus sp. A9 which separated and purified from soilhada high removal rate of Pb2+ in the water， and the adsorption kinetics and thermodynamic process of MBFA9 were further investigated. The results showed that the removal rate of Pb2+ reaches 92.73% at initial concentration of 56.2mg/L.The theoretical maximum capacity was 196.08mg/g， and the adsorption rate constant k2 was 0.019g/(mg·min-1).The dynamic characteristics of MBFA9 capturing Pb2+ in the water are in accordance with pseudo-second kinetic model， and the adsorption isotherm model of MBFA9 capturing Pb2+ agrees well with the Langmuir equation of thermodynamics with the correlation coefficient R2=0.96. Comparison among the IR spectra，SEM and EDS of MBFA9 capturing Pb2+ showed that the main component of MBFA9 is polysaccharides and the reaction mechanism is that functional groups on the surface of flocculant and Pb2+ formed chelate by chelation.There is chemical reaction between hydroxyl， amido， carboxyl and Pb2+ in the trapping process， and there is also a floc of sweep function， so MBFA9 has better removal effect on Pb2+. References | Related Articles | Metrics

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Comparative Study on Pyrolysis Characteristics and Dynamics Characteristics of Different Agriculture Biomass Wastes YAO Xi-wen， XU Kai-li， YAN Fang， HE Zhong-qi 2016, 37 (11):  1593-1597.  DOI: 10.12068/j.issn.1005-3026.2016.11.016 Abstract ( 643 )   HTML   PDF (760KB) ( 1102 )   For efficiently utilizing the agricultural biomass wastes through pyrolysis and gasification， thermogravimetric and mass spectrometry experimentation of corn cob， peanut shell， rice husk and rice straw were performed by thermogravimetric analysis and mass spectrometry. Mechanism of weightlessness， regularities of heat flow and the releasing combustible and small moleacule and small moleacule gases (CO， H2 and CH4) as well as the pyrolysis characteristics were thoroughly studied. The results showed that the weight loss of biomass mainly occurs within 220~410℃. As for corn cob， the weightlessness between 220℃ and 410℃ is the highest， which accounts for 80%~90% of the total weight loss. The pyrolysis index D is corn cob > rice straw > rice husk > peanut shell. The activation energy is rice husk > corn cob > rice straw > peanut shell. The char yield is rice husk > peanut shell > rice straw > corn cob. Generally， thermal stabilities of corn cob and rice straw are poor while thermal stabilities of rice husk and peanut shell are relatively stable. The activation energy and frequency factor are obtained by Coasts-Redfern method. Numerical results show a good consistency with thermogravimetric data. References | Related Articles | Metrics

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Topographical Distribution Characteristics of Vegetation Restoration in the Beiluo River Basin from 1995 to 2014 YAN Rui， ZHANG Xiao-ping，YAN Sheng-jun， ZHAO Wen-hui 2016, 37 (11):  1598-1603.  DOI: 10.12068/j.issn.1005-3026.2016.11.017 Abstract ( 516 )   HTML   PDF (1106KB) ( 670 )   Taking the Beiluo river basin as an example， the Landsat TM image data in 1995， 2007 and 2014 were employed and the vegetation coverage was derived to analyze how the vegetation restored.The results showed that the average vegetation coverage in the three years of the whole basin are 46.43%， 63.42%， and 73.4%， respectively. The trends of vegetation distribution on landform were analyzed in the upper reaches of the basin. It is showed that whatever the elevation belts， slope gradient spans， and slope aspect zones were， the vegetation coverage improved distinctively in 1995， 2007 and 2014. Meanwhile， the extent or the area of low vegetation coverage transforming to high vegetation coverage tends to be greater with the elevation lower， slope gradient larger， and slope aspect inclining to be shady. References | Related Articles | Metrics

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Effect of Particle Size Space Distribution in Coverage Rocks on Rocks Mixture YOU Xi， ZHANG Guo-jian 2016, 37 (11):  1604-1608.  DOI: 10.12068/j.issn.1005-3026.2016.11.018 Abstract ( 583 )   HTML   PDF (701KB) ( 587 )   In view of higher rocks mixture rate of ore drawing under the coverage rocks， a method describing the effect of particle size space distribution in coverage rocks on rocks mixture was proposed based on the degree of membership. On the basis of coverage rocks gradation， the model-experiment method was used to construct three sorts of coverage rocks’ particle size space distribution with identical gradation， and the degree of membership was used to quantify the model-experiment. Firstly， three sorts of particle size space distribution in coverage rocks were constructed. Then the degree of membership about specific subset was used to quantify the particle size space distribution in coverage rocks and rocks mixture process was estimated. Finally， the results of rocks mixture rate at equal ore drawing were compared. The model-experimental results showed that the method can reveal the effect of particle size space distribution in coverage rocks on rocks mixture， and it is a significant and helpful method to understand the process of rocks mixture and ore dilution. References | Related Articles | Metrics

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Stepwise Calculation Method of Dump Silt-Replacement Settlement Section HE Shun-you， YANG Chun-he， WANG Hong-xing 2016, 37 (11):  1609-1614.  DOI: 10.12068/j.issn.1005-3026.2016.11.019 Abstract ( 511 )   HTML   PDF (1472KB) ( 723 )   A stepwise calculation method for the silt-replacement settlement section is established in the background of a barrier dam. The silt-replacement instantaneous settlement is searched according to the stability of silt for different silt-replacement depth of the earlier dump. Then the silt consolidation settlement numerical analysis model under the compaction of the earlier and later dump is established and the final dump silt settlement section is got based on the Biot consolidation theory and the modified Cambridge model. The calculation results show that the final dump silt-replacement settlement section is positively correlated to the dump， the dump silt-replacement section appears to be an inverted trapezoidal. Finally， the corresponding calculation method is verified by detecting the real dump silt-replacement settlement section in the engineering by the high density resistivity method. References | Related Articles | Metrics

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Vertical Gob Group Blasting Dynamic Response Based on Structural Modal JIANG Li-chun， XIAO Kang， WU Ai-xiang， LI Ling-xin 2016, 37 (11):  1615-1619.  DOI: 10.12068/j.issn.1005-3026.2016.11.020 Abstract ( 650 )   HTML   PDF (657KB) ( 635 )   Discrete multi-freedom-degree dynamic response model of vertical gob group was developed. Based on structural modal， a new method analyzing gob group blasting response was presented. In combination with a typical engineering problem， verification and discussion were made for the method. Results indicate that the method can directly reflect gob group rock mass response law of displacement and velocity， and describe its blasting response characteristics. The results are in accordance with that of numerical simulation. For internal damping， rock mass vibration damping， the amplitude decays to zero gradually. Rock mass where the blasting loads act on has the strongest response strength. With an increase in the distance between rock mass and the blasting position， response strength of rock mass weakens. The method can greatly decrease computation time and increase calculation efficiency and it provides a new direction for dynamic response analysis of rock mass. References | Related Articles | Metrics

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Flash Flood Hazard Assessment in Coalmine Goaf Catchment CAO Chen， CHEN Jian-ping， SONG Sheng-yuan， ZHENG Lian-jing 2016, 37 (11):  1620-1624.  DOI: 10.12068/j.issn.1005-3026.2016.11.021 Abstract ( 582 )   HTML   PDF (1750KB) ( 643 )   The analytic hierarchy process (AHP) and the FFHIS (flash flood hazard index-based system)were applied for producing flash flood hazard zoning map in Xiqu gully by the ArcGIS software. The proposed index-based system processes information of seven parameters， namely， elevation， coalmine goaf risk zoning， waviness， vegetation types， rainfall intensity， soil types and slope angle. The assignment of different levels in the same parameter was based on the different severity. Based on the weight values， the data was superimposed to obtain the flash flood hazard zoning map. The historical flood events were used for validation. The validation showed that the flash flood hazard zoning map was consistent with the actual situations. The proposed index-based system and method were practical and effective for flash flood hazard assessment in Xiqu Gully. References | Related Articles | Metrics

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Initiation of Debris Flow in Tianjin Panlonggu Based on Artificial Rainfall SUN Dong-yan， CHEN Jian-ping， MA Yu-fei， SUN Tie 2016, 37 (11):  1625-1630.  DOI: 10.12068/j.issn.1005-3026.2016.11.022 Abstract ( 637 )   HTML   PDF (1156KB) ( 707 )   A debris flow physical model was established to study the starting-up characteristics， and then the initiation mode， recharge sources of provenance， the influence of rainfall on debris flow were studied. The results shows that the major provenance in debris flow forming area wont slide integrally when the debris flow starts up， but rather forming some gullies on the surface of the forming area， and the gullies develop until the debris flow starts up. It′s more dangerous in the case that the soil is saturated by small rainfall beforehand and then scoured by the moderate or heavy rainfalls. Unstable rock and soil mass on both sides of the gullies become the main recharge sources of provenance. The experimental results are well consistent with the natural Panlonggu debris flow. The research results can provide certain reference for building the early warning system and disaster prevention and reduction for Panlonggu debris flow and other similar debris flows. References | Related Articles | Metrics

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Mechanical Characteristics of Cemented Rockfill Materials with High Rock Block Proportions Under Uniaxial Compression ZHANG Yu-ning， CHEN Yu-long 2016, 37 (11):  1630-1634.  DOI: 10.12068/j.issn.1005-3026.2016.11.023 Abstract ( 522 )   HTML   PDF (883KB) ( 589 )   Artificial specimens of cemented rockfill materials with high rock block proportions (70%， 80%， 90%) were fabricated for uniaxial compression to understand the effects of rock block proportion and size effect on the failure modes and mechanical characteristics. The observed experimental phenomena were explained by numerical simulation. Results show that with the increase of rock block proportion， zones of both tensile stress and compressive stress develop as staggered distribution so that failure mode is dependent on the splitting failure and the shear failure. Increasing rock block proportion changes a tortuous failure surface contributed by splitting failure to multiple failure surfaces and detachment of rock particles along the periphery of specimens to form the compound failure mode combining splitting failure and shear failure. The size effect does not play any role in failure modes， but do play prominent role in mechanical characteristics. Mechanical properties of bigger samples are worse than those of smaller samples. References | Related Articles | Metrics

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Cavity Three-Dimensional Laser Scanning Point Cloud Data Processing Technology QIN Ya-guang， LUO Zhou-quan， WANG Wei， ZHENG Kai-huan 2016, 37 (11):  1635-1639.  DOI: 10.12068/j.issn.1005-3026.2016.11.024 Abstract ( 784 )   HTML   PDF (839KB) ( 900 )   Aiming at noise points in point cloud data detected by three-dimensional laser in cavity， curvature-chord ratio composite criterion was put forward for filtering and simplifying significant noise points. Besides， random filter algorithm was applied to reduce low frequency random noise points similar to the change of object. The piecewise low-order interpolation method was applied to fit cavity point cloud based on reduction and simplifying， thus the curve became smoother than before and after treatment. The application results show that the noise points in point cloud data detected by three-dimensional laser in cavity are effectively removed by filtering and smoothing treatment. Furthermore， the self-intersection in model is avoided. Therefore， cavity models generated by processed point cloud data are extremely identical to engineering practice. References | Related Articles | Metrics

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Analysis of Particle Shape Characteristics of Lunar Soil Simulant and Its Effect on Shear Strength LIN Cheng-xiang， ZHONG Shi-ying， LING Dao-sheng 2016, 37 (11):  1640-1644.  DOI: 10.12068/j.issn.1005-3026.2016.11.025 Abstract ( 607 )   HTML   PDF (844KB) ( 975 )   In order to study the effect of particle shape characteristics on shear strength， particles of lunar soil simulant are scanned and photographed with a stereo microscope. Then， a digital imaging processing software is used to statistically analyze the geometric characteristics of the particles. It shows that the particles of lunar soil simulant mainly are of four shapes: sphere， quasi-ellipsoid shape， quasi-trigonal shape and quasi-cube shape. Particles with the three irregular shapes are simulated as clumps in PFC 3D， and the numerical model of tri-axial test is obtained to study their shear strength. The numerical results show that: the particle shape has a noticeable effect on shear strength; the shear strength of particles of quasi-ellipsoid shape is the greatest of all， while the sphere particles has the minimum shear strength. For particles of the same quasi-trigonal shape， the greater ruggedness it is， the stronger shear strength the sample has. References | Related Articles | Metrics

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Study of Coarse Aggregate Configuration of Asphalt Mixture in Laboratory GUO Hui， ZHAO Yong-li， ZHOU Jian 2016, 37 (11):  1645-1649.  DOI: 10.12068/j.issn.1005-3026.2016.11.026 Abstract ( 628 )   HTML   PDF (1303KB) ( 609 )   In order to quantitatively evaluate the variation of the coarse aggregate alignment in the pitch mixture molding indoors， the digital image processing technology is used to propose a synthetic centroid moment method. The commonly used AC20 and SMA20 pitch mixtures are selected to define the number of rotations and compactions as test specimens of conditional molding for the two types of mixtures. Parameters are extracted through horizontal segmentation of the collected images. The synthetic centroid moments of the 2-D accumulate residual coarse aggregate and the 2-D non-accumulate residual coarse aggregate are computed， respectively. Results show that the synthetic centroid moments vary differently with the number of compactions for the two types of pitch mixture and coarse aggregate. The configuration of SMA20 is excellent after 60 compactions. References | Related Articles | Metrics

Mechanical Engineering

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Impact Analysis of Cantilever Beams Supported by MRE with Harmonic Excitation LIU Zi-liang， ZHAO Qian， WANG Chong-yang， WEN Bang-chun 2016, 37 (11):  1650-1654.  DOI: 10.12068/j.issn.1005-3026.2016.11.027 Abstract ( 632 )   HTML   PDF (893KB) ( 677 )   Using the adjustable and controllable characteristics of MRE (magnetorheological elastomers) under the action of applied magnetic fields， the structural support which takes MRE as the main elastic component was designed， and the cantilever beam’s impact fault experimental system with harmonic excitation was established based on the mode of shear force. Then， the experimental tests of vibration response under the action of control currents with different applied magnetic fields were carried out， and the performances of frequency shift and amplitude reduction of the system as well as the vibration response under the condition of impact were analyzed. The results showed that the stiffness of MRE is increased effectively with the control current， the controllability of natural frequency and amplitude of the system is then realized， and the severity of impact fault becomes controllable and the equipment life is thereby improved. References | Related Articles | Metrics

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Acoustic Performance of the Straight-Through Perforated Pipe Silencer Considering the Effect of Gas Flow FAN Wei， GUO Li-xin 2016, 37 (11):  1655-1659.  DOI: 10.12068/j.issn.1005-3026.2016.11.028 Abstract ( 622 )   HTML   PDF (1176KB) ( 993 )   In order to investigate the effect of gas flow on transmission loss (TL )， the finite element method (FEM) was used in conjunction with the computational fluid dynamics (CFD) to solve the problem of flow-sound coupling. The TL of the straight-through perforated pipe silencer was calculated using the CFD/FEM approach in the presence of gas flow， whose results were compared with the experimental data and predictions from the literature so as to validate the accuracy of the present study. It was concluded that with the increase of flow velocity ， the TL decreases remarkably at the resonance peak and increases at most frequencies， especially at the higher frequencies when the turbulence noise induced by gas flow is neglected， and with the increase of gas temperature， the TL curve shifts to higher frequencies. References | Related Articles | Metrics

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Random Response Analysis of Human Body-Seat System Based on the Finite Element Method DONG Rui-chun， GUO Li-xin 2016, 37 (11):  1660-1663.  DOI: 10.12068/j.issn.1005-3026.2016.11.029 Abstract ( 582 )   HTML   PDF (673KB) ( 765 )   The 3D finite element model of human body-seat system with driving postures including human skeleton， muscle， skin， seat， backrest and headrest was created based on the human anatomical anthropometry and the kinematics of human body. The initial boundary condition of driving postures of human body for dynamic analysis was provided by the static analysis of human body-seat system under the action of gravity. A sufficient number of modals for random response analysis were provided with the frequency extraction analysis. The model was validated by calculating the transfer function of lumbar disc to seat surface. Finally， the acceleration and stress response of lumbar disc under the action of white noise excitation of 0~20Hz on the seat bottom in the vertical direction were calculated， whose results showed that the peak response frequency of lumbar disc is less than its natural frequency as a result of seat coupling effect. The method can be used to replace experiments to research the response of human body-seat systems with different schemes. References | Related Articles | Metrics

Management Science

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Customer Delight and Customer Satisfaction: Which Better Drives Customer Loyalty? ZHANG Yue-xian， YANG Yong 2016, 37 (11):  1664-1668.  DOI: 10.12068/j.issn.1005-3026.2016.11.030 Abstract ( 631 )   HTML   PDF (357KB) ( 641 )   Delight and satisfaction are regarded as two important determinants of consumer loyalty. In the context of severe competition， great uncertainty and high risk， the predictive power of satisfaction and delight on customer loyalty was investigated， and the moderating role of online shopping experience was tested. It was found that delight and satisfaction work together to explain behavioral and attitudinal loyalty. Delight has a bigger impact on behavioral loyalty， and satisfaction exerts a bigger impact on attitudinal loyalty. Additionally， online shopping experience moderates the relationship among satisfaction， delight and loyalty. The findings can provide implications to improving customer loyalty by distributing limited resources. References | Related Articles | Metrics

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Spatial-Time Evolution of Carbon Emission Patterns in China: Based on Dynamic Evolution and Spatial Agglomeration TONG Xin， LI Xue-sen， TONG Lin， CHEN Kai 2016, 37 (11):  1668-1672.  DOI: 10.12068/j.issn.1005-3026.2016.11.031 Abstract ( 661 )   HTML   PDF (1805KB) ( 896 )   Aiming at the spatial correlation and difference of Chinese carbon emission， the spatial dependence and temporal transition path of Chinese regional carbon emission were analyzed with global spatial autocorrelation testing the spatial agglomeration was explored with local spatial autocorrelation testing， and the evolution of Chinese regional carbon emission scatter plot was studied based on Rey’s measurement of spatial and temporal transition . The results showed that there exists an inter-province correlation in Chinese carbon emission with a clustering pattern， which tends to increase gradually， and the spatial correlation of Chinese carbon emissions and the local regional structure are quite stable and path dependent. Therefore， the issue of Chinese carbon emission should be viewed objectively and rationally， the development of low-carbon economy and the policies of managing carbon emission in China should be considered both globally and dynamically from the spatial perspective. References | Related Articles | Metrics