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23 June 2021, Volume 42 Issue 6 Previous Issue    Next Issue
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Information & Control
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Information & Control

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Backstepping Control Method of Cascaded STATCOM Based on a Current Observer YU Hong-liang， WANG Xu， YANG Dan， LI Wei-jun 2021, 42 (6):  761-767.  DOI: 10.12068/j.issn.1005-3026.2021.06.001 Abstract ( 589 )   HTML ( 13)   PDF (528KB) ( 309 )   Aiming at the nonlinearity and uncertainty of the cascaded static synchronous compensator (STATCOM) system in power grid， a cascaded STATCOM backstepping control method was proposed based on a high gain adaptive observer. In order to estimate the output current value of STATCOM， an adaptive observer was designed based on neural network. The uncertain disturbance was estimated by introducing radial basis function (RBF) neural network. Through feedback design， the system was linearized. The back-stepping method was used to design the voltage controller. Based on Lyapunov’s asymptotic stability theory， the output reactive current control of cascaded STATCOM was obtained. The simulation and experimental results further verify the correctness and effectiveness of the proposed control method. References | Related Articles | Metrics

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Skeleton-based Action Recognition Method with Two-Stream Multi-relational GCNs LIU Fang， QIAO Jian-zhong， DAI Qin， SHI Xiang-bin 2021, 42 (6):  768-774.  DOI: 10.12068/j.issn.1005-3026.2021.06.002 Abstract ( 504 )   HTML ( 6)   PDF (900KB) ( 357 )   The interaction of human body parts in motion is diverse， but the existing skeleton-based action recognition methods with GCNs(graph convolutional networks) can only model a single relationship between joints. The idea of knowledge graphs was used to describe the different relationships between entities and a two-stream multi-relational GCNs action recognition method was proposed based on joints and body parts， by which the models of the natural connection relationship， symmetric relationship， and global relationship among nodes were established. The features of each relationship were synchronously transmitted and effectively fused in the network. In the process of global cooperation of human body parts， the interaction range of each part was limited and depends on specific actions. An adaptive topK global adjacency relationship calculation method was proposed based on Non-local algorithm， in which the nodes with the topK interaction strength were selected dynamically as the adjacent nodes for each node. The experimental results show that the proposed two-stream multi-relational network achieves good action accuracy on the Kinetics dataset and the NTU-RGB+D dataset. References | Related Articles | Metrics

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A Security-based CAN-FD Signal Packing Method DING Shan， BAO Lin-hui， GAO Meng-ning， SHE Li-huang 2021, 42 (6):  775-781.  DOI: 10.12068/j.issn.1005-3026.2021.06.003 Abstract ( 556 )   HTML ( 12)   PDF (534KB) ( 146 )   Modern vehicles are equipped with a large number of electronic devices， which may become a way for hackers to invade the vehicle network system. In order to prevent attacks， it is necessary to introduce a security mechanism for the CAN-FD vehicle bus. A CAN-FD hierarchical security model was established to distinguish signal， frame， and ECU-level security levels， based on frame AES encryption and adding MAC message authentication codes. According to the proposed model， a signal packaging safety constraint that can effectively reduce the hardware cost of ECU safety design was developed. By introducing the greedy algorithm into the crossover operator and mutation operator of the genetic algorithm， a safety-based hybrid genetic algorithm was designed to package and optimize CAN-FD signals with different safety levels. Experiments show that the hybrid genetic algorithm can achieve lower bandwidth utilization than the greedy algorithm， and the impact of this security design on bandwidth utilization is analyzed through experiments. References | Related Articles | Metrics

Materials & Metallurgy

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Effect of Quenching Temperature on Microstructure and Mechanical Properties of 12Cr14Ni2 Stainless Structural Steel ZHU Cheng-lin， GAO Xiu-hua， WANG Ming-ming， SONG Li-ying 2021, 42 (6):  781-788.  DOI: 10.12068/j.issn.1005-3026.2021.06.004 Abstract ( 857 )   HTML ( 18)   PDF (10913KB) ( 194 )   Effect of quenching temperature on microstructure and mechanical properties of a 12Cr14Ni2 sorbite stainless steel was investigated by optical microscopy， scanning electron microscopy， electron probe and transmission electron microscopy， respectively. The results show that the fine and uniform tempered sorbite structures can be obtained in the hot-rolled steel plate after quenching at 900~1050℃ for 0.5h and tempering at 710℃ for 2h. There are a large number of Cr-riched M23C6 precipitates at the grain boundaries of tempered sorbite with a diameter of 100~200nm. As the quenching temperature increases from 900℃ to 1050℃， the austenitic grain size gradually increases after quenching， resulting in the coarsening of the tempered sorbite structure after heat treatments. The strength of the experimental steel first decreases and then increases， and both the elongation and impact energy increase first and then decrease. The excellent mechanical properties can be obtained at an optimal quenching temperature of 950℃， corresponding to the tensile strength of 767MPa， the yield strength of 588MPa， the elongation after fracture of 22%， and the impact energy of 107J at 20℃. References | Related Articles | Metrics

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Efficient Recovery of Highly Concentrated Ammonia Nitrogen from Vanadium-extraction Wastewater with MAP Method ZHOU Su-ying， DING Xue-yong， XUE Xiang-xin， YANG He 2021, 42 (6):  789-794.  DOI: 10.12068/j.issn.1005-3026.2021.06.005 Abstract ( 626 )   HTML ( 9)   PDF (1270KB) ( 206 )   In order to realize the efficient recovery of ammonia nitrogen from vanadium-extraction wastewater， influencing factors including phosphorus source， magnesium source， pH value， reaction time and the molar ratio of n(Mg)∶n(N)∶n(P) were investigated. The Box-Behnken response surface method was then used to optimize the modeling and XRD was used to analyze the products. The results indicated that MgCl2·6H2O and Na2HPO4·12H2O were used as the most suitable source of magnesium and phosphorus， and the best precipitation time was 20min. The polynomial regression equation obtained with the Box-Behnken response surface method showed that the influence degree of each factor on the ammonia recovery percent was n(Mg)∶n(N)＞n(P)∶n(N)＞pH. The confirmatory experiment was carried out around the optimal conditions， and pH， n(Mg)∶n(N) and n(P)∶n(N) were 9.51， 1.22 and 1.12， respectively. The recovery percent of ammonia nitrogen was 98.32%， and the effect of model optimization was obvious. In summary， the optimization of MAP with the response surface method for the high-efficiency recovery of ammonia nitrogen in vanadium extraction wastewater is of great significance， especially for the efficient resource utilization of high ammonia-nitrogen wastewater in the expanded vanadium-extraction industry. References | Related Articles | Metrics

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Leaching of High-Alkaline Gangue Low-Grade Copper Oxide Ore in (NH4)2SO4-NH3-H2O Solution XIAO Fa-xin， PENG Yu， SUN Shu-chen， TU Gan-feng 2021, 42 (6):  795-801.  DOI: 10.12068/j.issn.1005-3026.2021.06.006 Abstract ( 629 )   HTML ( 10)   PDF (1411KB) ( 197 )   A low-grade copper oxide ore with highly alkaline was treated. According to the characteristics of the solution with the high content of calcium and magnesium， ammonia-ammonium sulfate leaching system was adopted to conduct leaching experiment for recovering copper from a low-grade oxidized copper ore. The thermodynamic model of Cu2(OH)2CO3-(NH4)2SO4-NH3-H2O was established in the leaching system of malachite (Cu2(OH)2CO3) under the condition of double conservation of mass and charge. The fitting function of the Matlab software and the diff and solve functions were used to calculate the optimal ammonia concentration and total copper ion concentration of malachite under different ammonium sulfate concentrations， respectively. Parameters， such as ammonia concentration， ammonia-ammonium ratio and liquid-solid ratio were optimized. The results indicate that the appropriate conditions include an ammonia concentration of 1.2mol/L， an ammonia-ammonium ratio of 2∶1 and a liquid-solid ratio of 3∶1. Under these conditions， the copper leaching rate reaches ~70%. The calculated results are basically consistent with the experimental measurements. References | Related Articles | Metrics

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Analysis of Attrition Index of the Smelter Grade Alumina Particle YANG You-jian， QI Jun-feng， PANG Xiao-juan， WANG Zhao-wen 2021, 42 (6):  801-806.  DOI: 10.12068/j.issn.1005-3026.2021.06.007 Abstract ( 616 )   HTML ( 10)   PDF (622KB) ( 201 )   In order to ensure an efficient transportation and smooth feeding of the smelter grade alumina， certain particle size distribution and attrition index of the alumina are required. The attrition resistance of the smelter grade alumina is studied and discussed. The particle size distribution and attrition index of 32 alumina samples collected from different alumina plants were measured and calculated by using a self-made alumina attrition index analyzer. The relationship between alumina attrition index and particle size distribution was analyzed. The experimental results emphasized the importance of the combination of the attrition index and particle size distributions. Meantime， the attrition rate of alumina in the dry scrubbing system was analyzed. A method was proposed to evaluate the particle size distribution of alumina. References | Related Articles | Metrics

Mechanical Engineering

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Reliability Analysis of Aero-engines Based on Multivariate Degradation Modeling Under Competitive Failure WANG Xin-gang， SHEN Qiang， HAN Kai-zhong， WANG Chao 2021, 42 (6):  807-814.  DOI: 10.12068/j.issn.1005-3026.2021.06.008 Abstract ( 635 )   HTML ( 13)   PDF (480KB) ( 436 )   In order to solve the problem of aero-engines’ reliability evaluation of multi-degraded systems under competitive failure， a reliability evaluation method of related competitive failure between multi-degraded failure and sudden failure is proposed. The non-linear Wiener process and Gamma process with random effects are used to describe the degenerate failure process of the system， the appropriate Copula function is chosen to model the failure correlation of the multivariate degenerate system， and parameter of multivariate degradation-related failure model is estimated by Markov chain Monte Carlo method. The Weibull distribution is introduced to describe the sudden failure time， the proportional hazard model is used to construct the sudden failure rate function about the performance degradation， and the two-step maximum likelihood estimation method is used to identify the model parameters. Combined with the performance degradation data of aero-engines， the reliability evaluation of the multivariate degradation system under competitive failure is realized， and the validity and accuracy of the model are verified through the analysis results. References | Related Articles | Metrics

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Availability-centered Maintenance Policies for Degrading Manufacturing Systems Considering Product Quality ZHOU Bing-hai， SHI Yu， ZHANG Yu-xian 2021, 42 (6):  814-820.  DOI: 10.12068/j.issn.1005-3026.2021.06.009 Abstract ( 462 )   HTML ( 2)   PDF (498KB) ( 198 )   In order to reduce system unplanned downtime and control product quality， an availability-centered preventive maintenance strategy of the multi-component production system is proposed. Firstly， three preventive maintenance methods are defined， whose influence on the equipment state is studied so as to establish a reliability model. On the basis of Markov state analysis of the system， the relationship between product quality and system degradation state is established， and the total cost model including quality loss cost is constructed. From the perspective of practical application， the reliability and maintainability of equipment are taken into consideration. Thus， an availability-centered preventive maintenance strategy of the system is planned when the goal is to minimize the total cost. Results indicate that the maintenance strategy proposed can be effectively applied to the multi-component production system， and the effect of the multi-operation preventive maintenance method is better than that of single operation. References | Related Articles | Metrics

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Analysis of Aerodynamic Characteristics of Bionic Flapping Wing Aircraft Based on XFlow ZHANG Zhi-jun， CHEN Mo， YANG He-jie， SUN Ji-yu 2021, 42 (6):  821-828.  DOI: 10.12068/j.issn.1005-3026.2021.06.010 Abstract ( 1032 )   HTML ( 38)   PDF (1973KB) ( 1269 )   The bionic flapping wing motion is realized by the rapid return characteristic of space crank and rocker structure. In order to explore the influencing factors of the aerodynamic characteristics of bionic flapping aircraft， the particle tracking method of Boltzmann model is adopted to simulate the aerodynamic characteristics during flapping. Based on the computational fluid dynamics simulation software XFlow， a simulation analysis is carried out for different airfoils， wingspan and wing plane shapes and the influence on lift and thrust is explored. The results show that the lift coefficient of the flapping wing aircraft increases with the rise of the airfoil curvature and wingspan， and the thrust coefficient decreases with the increase of the bending degree. Through the comprehensive analysis， it is found that when the wingspan length is 2.5 times the chord length， the aerodynamic characteristics are the best. Wings with different wing surface shapes have different aerodynamic characteristics. Compared with the trailing edge geometry， the leading edge has a greater impact on the aerodynamic characteristics. References | Related Articles | Metrics

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Comparison of Three Stage-Wise Superstructures of Water Network Based on Particle Swarm Optimization LIU Shi-qi， SONG Jin-chun， YANG Bin 2021, 42 (6):  829-834.  DOI: 10.12068/j.issn.1005-3026.2021.06.011 Abstract ( 411 )   HTML ( 6)   PDF (526KB) ( 155 )   Based on the stage-wise superstructure model of the heat exchanger network， three improved cooling water exchange networks are proposed. The hot and cold utilities are dispensable and the cold stream only contains cooling water， which is different from the traditional heat exchanger synthesis. The three design approaches all consider the water splitting and mixing to achieve the non-isothermal mixing of water. The second and third configuration can achieve phased water mixing. The minimum total annual cost is determined by the trade-off utility cost and capital cost. Particle swarm optimization (PSO) is demonstrated to optimize the heat load and the water mass flow rate in the water network. Two cases show that the total annual cost of the three improved structures proposed is better than the previous research results and in Case 1， configuration 3 has the lowest cost， and in Case 2， configuration 1 has the best economic performance. References | Related Articles | Metrics

Resources & Civil Engineering

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Comparative Study on the Fluid Inclusion in Jiangjiatun and Lanjiagou Mo Deposits in the Liaoxi Area LI Ming， WANG Guo-guang， ZHANG Yong-li， GONG En-pu 2021, 42 (6):  835-841.  DOI: 10.12068/j.issn.1005-3026.2021.06.012 Abstract ( 419 )   HTML ( 4)   PDF (4955KB) ( 137 )   Based on the fluid inclusion study on the Jiangjiatun and Lanjiagou Mo deposits， two distinctive ore-forming fluids were identified. Fluid inclusions in the Jiangjiatun Mo deposit are characterized by type Ⅰ two-phase aqueous inclusions， with homogenization temperatures from 163 to 234℃ and salinity values from 3.06% to 6.01%. It indicates that ore-forming fluids are moderate-low homogenization temperature and salinity. Fluid inclusions in the Lanjiagou Mo deposit are featured by type Ⅱ CO2-bearing fluid inclusions， indicating a deep formation environment. Microthermometric data in the Lanjiagou Mo deposit show homogenization temperatures from 200 to 283℃ for type Ⅰ inclusions and from 281 to 346℃ for type Ⅱ inclusions， and salinities from 2.74% to 7.31% for type Ⅰ inclusions and from 3.52% to 4.80% for type Ⅱ inclusions. In view of the above research results， it is believed that the discovered ore bodies in the Jiangjiatun deposit were formed in a much shallower environment with lower homogenization temperature and salinity than the Lanjiagou Mo deposit. It indicates that it is possible to find Mo orebodies at depth beneath the exposed ore bodies. References | Related Articles | Metrics

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Extraction Method of Open Pit Mine Car Based on UAV Point Cloud Data MAO Ya-chun， FU Yu-wen， CAO Wang， ZHAO Zhan-guo 2021, 42 (6):  842-849.  DOI: 10.12068/j.issn.1005-3026.2021.06.013 Abstract ( 500 )   HTML ( 19)   PDF (3158KB) ( 332 )   In order to solve the key problem that the existence of the mine car point sets in open pit decreases the accuracy of the UAV point cloud data， an automatic extraction method of the mine car point sets in open pit stope was proposed. Using the UAV point cloud of the Yabaling open pit as the data source， the ground points and non-ground points were distinguished using the progressive morphological filtering algorithm， then the set of mine car points were extracted from the non-ground points by clustering them with an improved Euclidean clustering algorithm， and finally the mine car extraction results were evaluated and analyzed based on the error criterion proposed by the International Society for Photogrammetry and Remote Sensing (ISPRS). The results show that the method can effectively extract the set of mine car points in the open pit， and can provide an important technical support for fast and efficient check and acceptance of the open pit. References | Related Articles | Metrics

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Study on Ground Surface Settlement due to Pipe Jacking of Circular Steel Pipes with Flange Plates WANG Zhi-guo， ZHAO Wen， DONG Jia-chao， JIANG Bao-feng 2021, 42 (6):  849-856.  DOI: 10.12068/j.issn.1005-3026.2021.06.014 Abstract ( 451 )   HTML ( 2)   PDF (1325KB) ( 170 )   Due to the advantages of the circular steel pipes with flange plates in forming underground support structures compared with the traditional pipe jacking method， it has already been used to construct urban underground spaces. However， due to the existing of the flange plates， the earth pressure around the pipe is complicated， thus the ground surface settlement during jacking process is quite different from that of the circular pipe. The effect of the earth pressure around the circular steel pipe with flange plate was studied and the ground deformation formula caused by the friction around the pipe during the jacking process was derived using the Mindlin solution based on elastic mechanics as well as the coordinate conversion theory. By taking the Olympic Sports Center Station of Shenyang Metro Line 9 as an example， the Midas finite element analysis software was used to simulate the jacking process of the circular steel pipes with flange plate. It is found that the cross-section ground surface becomes a “U”-shaped settlement groove. The surface settlement of the monitoring points at the longitudinal section gradually increases with the disturbance of the pipe jacking， and the ground deformation tends to be stable after the head of the jacking pipe exceeds the monitoring surface by the length of the pipe element. The influence of the soil cohesion and the internal friction angle on surface settlement during the jacking process was also analyzed. References | Related Articles | Metrics

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Influence of Excavation Sequence on the Vertical Soil Pressure on PBA Subway Station JIA Peng， GAO Deng， LIU Dong-qiao 2021, 42 (6):  857-863.  DOI: 10.12068/j.issn.1005-3026.2021.06.015 Abstract ( 435 )   HTML ( 4)   PDF (1609KB) ( 116 )   By taking the Dongsi PBA station of Beijing Metro Line 6 as an example， the influence of the excavation sequence on the distribution of the vertical earth pressure on the pilots and the station arches was analyzed respectively. The results show that soil pressure on the station arches is bias， and the vertical earth pressure at the arch feet of the outer side pilots is 1.27 times than that at the inner side pilots. The vertical earth pressure at the outer arch feet of the upper and lower side pilots is about 1.1 times and 1.2 times of the gravity stress respectively. The vertical earth pressure on the central pilots is affected by the excavation sequence of the pilots in the same level， and is larger on the later constructed pilots. The vertical earth pressure on the station arch is mainly affected by the construction sequence of the arches. In the “first edge and then middle pilot” construction plan， the vertical earth pressure on the crown arches of the station fluctuates as such that the vertical earth pressure on the side span can be as low as 0.77 times the gravity stress， while the vertical earth pressure at the junction of the arch and the central pilot can be as high as 1.05 times the gravity stress. References | Related Articles | Metrics

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TBM Tunnel Shaping Quality Detection Method and Its Application Based on Point Cloud XIA Yi-min， GUO Zi-luo， DENG Chao-hui， LONG Bin 2021, 42 (6):  864-870.  DOI: 10.12068/j.issn.1005-3026.2021.06.016 Abstract ( 595 )   HTML ( 7)   PDF (796KB) ( 331 )   Taking the surrounding rock of TBM tunnel as a research object， the 3D laser scanning technology is used to detect the shaping quality of TBM tunnel. An automatic detection method of TBM tunnel shaping quality was proposed based on the 3D laser scanning technology. The 3D scanning device composed of a Pan-Tilt and a 2D laser scanner is installed on the main beam of the TBM. The Pan-Tilt can quickly rotates 90° towards the cutter head with the 2D laser scanner， and can convert the 2D point cloud acquired by the scanner into a 3D point cloud in real time， then the computer performs preprocessing， such as tunnel axis calculation， filtering and interception on the point cloud， and calculates the flaking and collapse of the surrounding rock using section extraction and piecewise cubic Hermite interpolating polynomial. Parameters of the tunnel shaping quality can be given， thus the tunnel shaping quality can be accessed. The feasibility of the TBM tunnel shaping quality detection method was verified through an engineering example. By adopting this method， the tunnel shaping quality can be detected simultaneously during the TBM construction process， and a digital measurement system can be formed. References | Related Articles | Metrics

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Mechanical Properties of Shear Keys of Segment Joints in Immersed Tunnels Under Seismic Loading HE Cong， XU Guo-yuan， ZHANG Zhi-gang 2021, 42 (6):  871-878.  DOI: 10.12068/j.issn.1005-3026.2021.06.017 Abstract ( 561 )   HTML ( 7)   PDF (1094KB) ( 256 )   On the basis of finite element method combined with viscous-elastic artificial boundary， the seismic wave input was transformed into equivalent node force， and a three-dimensional plane SV wave input method based on wave theory was established. The accuracy of seismic wave input method and the valid of the numerical analysis were proved by the half-space example. Then the mechanical properties of the shear keys of the segment joint in Hong Kong-Zhuhai-Macao Bridge immersed tunnel considering the static and dynamic water effects of the upper sea water were studied based on the established seismic wave input method. The results show that the vertical acceleration is also generated by horizontal earthquake， but the value of the vertical acceleration is small. The compressive stress is the largest stress on the shear key under earthquake， while the tensile stress is relatively small. Because the tensile stress of shear key is mainly concentrated on the locations where the shear key is connected with the main body of the immersed tunnel， tensile cracks are prone to occur. The main failure mode of horizontal shear keys is tensile failure. The setting direction of the shear key in the joint determines the shear distribution at the root of the shear key， and most of the shear forces are resisted by the shear key in the same direction with the displacement. References | Related Articles | Metrics

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Full Scale Loading and Unloading Test and Simulation on Squat Silo with Ground Conveying Corridor SUN Wei-wei， FENG Jun， MAO Feng-tao， WANG Chen-chen 2021, 42 (6):  879-886.  DOI: 10.12068/j.issn.1005-3026.2021.06.018 Abstract ( 385 )   HTML ( 5)   PDF (1825KB) ( 152 )   In order to study the pressure distribution and evolution of the wall and the corridor in the squat silo with ground conveying corridor， a full-scale silo loading and unloading test and simulation were carried out. It was found that the pressure distribution at the bottom of the wall is affected by the existence of the corridors. The pressure of the corridor is related directly to the actual height of the stored material above it. Rankine’s coefficient of active earth pressure is more suitable to predict the lateral pressure on the wall and the corridor. The basis for distinguishing the deep and shallow buried tunnels is not applicable to the conveying corridor in the squat silo where the arch effect of the stored material is not obvious. The predicted value of the top wall pressure on the corridor according to highway tunnel code and Terzaghi’s theory is far from the actual test value. It is more reasonable and safer to use the corridor pressure calculation formula proposed in this paper based on the shallow buried theory. There are different degrees of overpressure on the top wall and the side wall of the main and secondary corridors during eccentric discharge. It is recommended that the overpressure coefficient of the corridors should be properly considered when calculating the discharge load in squat silos. References | Related Articles | Metrics

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Study on Seismic Performance of Rubber Concrete and Conventional Concrete Composite Pile GAO Xing， JIA Jin-qing， WANG Wei-yu， ZHANG Li-hua 2021, 42 (6):  886-892.  DOI: 10.12068/j.issn.1005-3026.2021.06.019 Abstract ( 518 )   HTML ( 5)   PDF (1024KB) ( 105 )   In earthquake， the pile foundation is often damaged due to the insufficient bending moment resistance and excessive displacement. In order to improve the seismic performance of the pile foundation， a composite pile with rubber concrete at the top and conventional concrete at the bottom was developed. In order to analyze the seismic performance of composite piles， a drop hammer was used to simulate the earthquake source， and a full-scale field test was conducted on the composite piles. The results show that load on the pile top can enhance the seismic performance of the pile foundation. In the test， when the ratio of the rubber concrete pile length to the total pile length is less than 1/6， the depth of the load constraint effect is equal to the rubber concrete pile length. When the ratio of the rubber concrete pile length to the total pile length is more than 1/6， the depth of the load constraint effect is a constant of 1/6 of pile length. The damping effect of the rubber concrete pile is significant if the pile is close to the earthquake source， while it decreases with the increase of the distance from the seismic source， and the rubber concrete section of the pile no longer plays a role in the whole length. The fitting curve of the damping efficiency and the ratio of the rubber concrete pile length to the total pile length is S-shaped. During the seismic design， it is not suitable to continuously increase the length of the rubber concrete pile to improve the seismic performance of the pile. References | Related Articles | Metrics

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Development Efficiency Evaluation and Optimization of Shenyang Real Estate Industry QI Xi-jing， ZHANG Jing-yu， JI Hong-nan 2021, 42 (6):  893-899.  DOI: 10.12068/j.issn.1005-3026.2021.06.020 Abstract ( 364 )   HTML ( 3)   PDF (967KB) ( 160 )   The development efficiency of the real estate industry is defined as the relative effective degree of transformation between input resources factors (land and capital) and output factors of the real estate development industry. The enhanced efficient DEA model is used to measure and analyze the development efficiency of Shenyang real estate industry by selecting the purchased land area and real estate development investment as the input indicators and the commercial housing sales area， commercial housing sales and land value-added tax as the output indicators. The results show that the development efficiency of Shenyang real estate industry is relatively low. Therefore， countermeasures and suggestions to optimize the development efficiency are put forward from the perspective of policies and enterprises in order to promote the transformation and upgrading of the industry. References | Related Articles | Metrics

Management Science

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Auction Mechanism Chosen by Third Party Logistics Suppliers Based on Risk Aversion REN Rong-rong， WANG Bo， LU Fu-qiang， LI Wei-xin 2021, 42 (6):  900-908.  DOI: 10.12068/j.issn.1005-3026.2021.06.021 Abstract ( 424 )   HTML ( 8)   PDF (574KB) ( 171 )   In the past， when researchers studied the selection of third-party logistics suppliers(3PLS)， it was generally assumed that third-party logistics suppliers have a risk-neutral attitude towards fourth-party logistics integrators(4PLI)， which is often inconsistent with reality. In order to make the research more realistic， considering that the third-party logistics providers have a risky attitude， the fourth-party logistics integrators select the third-party logistics suppliers through a multi-attribute reverse auction. Through case design and related experiments， it is found that the risk attitude is measured by the risk measurement method of conditional value at risk (CVaR)， which integrates risk factors into the multi-attribute reverse auction， breaking the traditional assumption that the fourth-party logistics integrators assume risk neutrality when selecting them. Moreover， the commonly used CVaR method in risk measurement is integrated into supplier selection， which is innovative. Comparing different levels of risk aversion and risk neutrality， the result shows that 4PLI is the most beneficial when 3PLS is risk-neutral， and when 3PLS is under risk aversion， the lower the degree of risk aversion， the more beneficial it is for 4PLI. References | Related Articles | Metrics