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15 July 2019, Volume 40 Issue 7 Previous Issue    Next Issue
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Information & Control
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Information & Control

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A Searchable Encryption Scheme for Encrypted Large Data Sets JIA Qiang， ZHANG Shuai， ZHOU Fu-cai 2019, 40 (7):  913-919.  DOI: 10.12068/j.issn.1005-3026.2019.07.001 Abstract ( 970 )   HTML   PDF (415KB) ( 1060 )   In order to solve the problem of high keywords-search time-complexity caused by excessive security indexes in symmetric searchable encryption scheme， combined with the cloud storage application environment， a new searchable encryption (SE) scheme for encrypted large data sets in distributed environments was presented. The scheme was aimed at data owners who have large sizes of files in the cloud storage application environment. By using block storage structure to optimize the structure of security index， the security indexes were divided into three categories: Small， Medium， and Large， according to the block parameters. And with the method of register indirect addressing， the scheme can maintain good search time complexity in the case of large security index， and be acceptable for users. The experimental result shows that the keyword search time reaches sublinearity as the security index increases. References | Related Articles | Metrics

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Underdetermined Blind Source Separation Algorithm Based on Directional Amplitude Ratio JI Ce， JIANG Yu-tian 2019, 40 (7):  920-924.  DOI: 10.12068/j.issn.1005-3026.2019.07.002 Abstract ( 687 )   HTML   PDF (507KB) ( 620 )   In order to improve the estimation accuracy of mixed matrix in underdetermined blind source separation， an underdetermined blind source separation algorithm based on directional amplitude ratio of mixed signal data in frequency domain was proposed. In order to make full use of the phase information of data points of complex mixed signals， the directional amplitude ratio of complex signals was introduced， and the screening of single source points was accurately implemented by the variance， mean and distribution density of directional amplitude ratio of the complex mixed signals. The single source points was disposed with unitization and projection， the ratio of column elements of a mixed matrix was obtained through clustering analysis to estimate the mixed matrix. Finally， the matching pursuit algorithm was used to reconstruct the source signal. The simulation results show that the algorithm proposed can obtain more precise mixed matrix and separated signals compared with the comparison algorithms. References | Related Articles | Metrics

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Plane Wave Ultrasonic Imaging Algorithm Based on Improved DMAS and Its GPU Implementation BAO Xi-rong， SHEN Xiao-yan， ZHANG Shi， SU Ting 2019, 40 (7):  925-931.  DOI: 10.12068/j.issn.1005-3026.2019.07.003 Abstract ( 899 )   HTML   PDF (1694KB) ( 1305 )   The contrast signal-to-noise ratio(SNR) of the image synthesized by the plane wave ultrasonic imaging algorithm based on DMAS beamforming is low and the real-time imaging problem cannot be realized due to the complexity of the algorithm.A new plane wave ultrasonic imaging algorithm named DSBMGCF(delay sum before multiply and generalized coherence factor) with higher imaging quality and less complexity of calculation was proposed. Then， the simulation experiment of point target and cyst target were done on Matlab by FieldII simulation tool. The imaging quality of the algorithm was verified. At the same time， the proposed algorithm was parallelized and improved， and a parallel algorithm for plane wave ultrasound imaging， PDMASGCF(parallel delay multiply and sum generalized coherence factor)， which is suitable for parallel implementation on GPU was obtained. Finally， on the ordinary workstation Dell T7810 in the laboratory， the verification experiments on time and quality of imaging were carried out. Higher imaging frame rate was obtained， while better imaging performance was guaranteed. References | Related Articles | Metrics

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A Modified KNN Classifier for Unbalanced Dataset LIU Peng， DU Jia-zhi， LYU Wei-gang， DOU Ming-wu 2019, 40 (7):  932-936.  DOI: 10.12068/j.issn.1005-3026.2019.07.004 Abstract ( 810 )   HTML   PDF (399KB) ( 746 )   The existing arrhythmia datasets are suffering from the unbalanced number of training sample for electrocardiogram(ECG) data due to the obvious difference among the sample number of different types. A novel KNN-based classification algorithm， i.e.， a modified kernel difference-weighted KNN classifier(MKDF-WKNN) was proposed， by introducing a correction factor to restrain the weights of the categories with more samples and increase the weights of the categories with fewer samples. The experiment was carried on the UCI arrhythmia dataset to classify the ECG data. The results show that， for unbalanced datasets the proposed algorithm is better than some other KNN-based algorithms such as KNN， DS-WKNN， DF-WKNN and KDF-WKNN， in terms of classification accuracy. References | Related Articles | Metrics

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Driver Drowsiness Detection Algorithm Using Short-Time ECG Signals XU Li-sheng， ZHANG Wen-xu， PANG Yu-xuan， WU Cheng-yang 2019, 40 (7):  937-941.  DOI: 10.12068/j.issn.1005-3026.2019.07.005 Abstract ( 933 )   HTML   PDF (427KB) ( 1107 )   Heart rate variability analysis is used extensively for detecting driver drowsiness based on ECG signals. However， this method is deficient in accuracy and needs long-time ECG signal. An algorithm for driver drowsiness detection based on short-time ECG signals was proposed. First， the original ECG signal is rearranged into 30s segments， after which the R-wave positions are extracted using differential threshold algorithm and the noisy segments are excluded according to the calculated R-R interval. Then， time and frequency domains’ features of R-R interval series were extracted and combined with the features obtained by the deep convolutional neural network model with pre-trained weights of ImageNet dataset. Finally， random forest classifier was employed to detect the fatigue status of drivers based on the extracted features. The results demonstrate that the proposed algorithm has good performance in detecting driver drowsiness， with an averaged overall accuracy of 91%. The proposed algorithm needs shorter ECG signals and has higher accuracy in detecting driver drowsiness. References | Related Articles | Metrics

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Research on Advertising Conversion Rate Based on Hybrid Model LI Xiong-fei， ZHOU Jin-nan， ZHANG Xiao-li 2019, 40 (7):  942-947.  DOI: 10.12068/j.issn.1005-3026.2019.07.006 Abstract ( 700 )   HTML   PDF (519KB) ( 744 )   Many existing models of predicting advertising conversion rate lack research on the interaction among deeper features. Hence， a new hybrid model was proposed for this problem. High-level combination features were extracted using a light gradient boosting machine(LightGBM) model， and combining with the advantages of field-aware factorization machines(FFM) model. It can effectively process sparse data and predict the conversion rate. In order to verify the effectiveness and generalization ability of the hybrid model， the model was tested on two data sets for discussing the influence of parameters on model prediction results and was compared with other models. The experimental results show that the hybrid model is more accurate. References | Related Articles | Metrics

Materials & Metallurgy

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Effect of Austempering Process on Microstructure and Mechanical Property of Ultra-high Strength Bainitic Steel YAO Chun-xia， LAN Hui-fang， DU Lin-xiu 2019, 40 (7):  948-952.  DOI: 10.12068/j.issn.1005-3026.2019.07.007 Abstract ( 799 )   HTML   PDF (982KB) ( 759 )   The effect of different austempering processes on microstructure evolution and mechanical property of low carbon ultra-high strength bainitic steels was studied. The results show that compared with the one-stage austempering process， the amount of bainite increases and the content of martensite decreases in the two-stage process， which result that the yield strength of the experimental steel increases 58% and is up to 1178MPa， the elongation increases from 7.7% to 14.4% and the impact toughness increases 16% and reaches 66J/cm2. Comparing the strength and plasticity matching of the corresponding experimental steels under different heat treatments， it is found that the product of strength and elongation of the steel can reach 21888MPa·% under the A3(240℃for 2h and then 270℃for 1h) two-stage process condition. Under the two-stage process conditions， the martensite band due to Mn segregation in the steel can be eliminated and a relatively uniform bainite structure can be obtained， so that the strength and toughness of the experimental steel can be improved simultaneously. References | Related Articles | Metrics

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Calculating Strip Coil Heating Temperature in the Warm-Rolling Process for Difficult-to-Deform Metals JIAO Zhi-jie， YAN En-bo， LI Jian-ping 2019, 40 (7):  952-955.  DOI: 10.12068/j.issn.1005-3026.2019.07.008 Abstract ( 602 )   HTML   PDF (813KB) ( 661 )   A warm-rolling mill with two hot coil boxes was designed to process difficult-to-deform metals strip. A numerical model was built to calculate strip coil temperature in a two dimensional cylindrical coordinate system， which considered the heat transferring along radial and axial directions. The thermal conductivity coefficient of radial direction was calculated according to the structures of strip layer， oxide layer and interface layer. The axial and radial explicit and implicit differential equations were deduced by finite differential method， solved by the alternating direction implicit method(ADI). The boundary condition of heat transfer coefficient was dominated by radiation mechanism， where a correction coefficient was introduced to consider other factors. The strip coil heating temperature was firstly measured through experiment. Then a linear relation between the actual temperature and heating time was regressed. After using the correction coefficient of heat transfer optimized by the actual temperature， the temperature can be calculated by the model， with the error within ±2℃ compared with the experimental temperature. References | Related Articles | Metrics

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Direct Quenching After Rolling and Tempering Processes of Fe-Mn-1.6Ni-C Steel Plate for Hydropower Station CHEN Jie， LI Chang-sheng， LI Kun， TU Xing-yang 2019, 40 (7):  956-961.  DOI: 10.12068/j.issn.1005-3026.2019.07.009 Abstract ( 784 )   HTML   PDF (2200KB) ( 647 )   The microstructure and mechanical properties of Fe-Mn-1.6Ni-C steel plate after direct quenching and tempering were investigated， where the tested steel was processed by controlled rolling， direct quenching and 560~710℃ tempering. The results show that the fine lath-martensite is obtained by direct quenching after rolling and the improved tensile strength of the experimental steel after direct quenching is mainly from solid solution strengthening. After tempering， the tensile strength of the steel decreases and the yield strength increases， which is mainly caused by the carbide precipitation and the pinning effect of the precipitates on the dislocations. Due to the aggregation and growth of carbides and recovery and recrystallization of ferrite， the strength decreases and the impact toughness increases with the increasing temperature of tempering. However， the coarse carbides can be observed in the steel if the temperature of tempering is higher than A○c1， which facilitate the nucleation of micro-cracks and decrease the impact toughness. An optimum tempering temperature of Fe-Mn-1.6Ni-C steel can be obtained， which is 680℃， associated with the yield strength of 963MPa， the tensile strength of 988MPa， the elongation of 20.0%， and the -60 ℃ impact energy of 142J. References | Related Articles | Metrics

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Numerical Simulation of Methane-Air Premixed Combustion Process in a Randomly Packed Bed JIANG Lin-song， LIU Hong-sheng， WU Dan， XIE Mao-zhao 2019, 40 (7):  962-967.  DOI: 10.12068/j.issn.1005-3026.2019.07.010 Abstract ( 651 )   HTML   PDF (1377KB) ( 677 )   Three dimensional random geometric structure of pellets packed bed was modeled using the discrete element software LIGGGHTS. Large eddy simulation method， two-temperature model and EBU-Arrhenius combustion model were employed to simulate the premixed combustion process of methane-air in the randomly packed bed. The calculated results are compared with experiment data to verify effectiveness of the model. The structure and the shape of the flame and the temperature distribution in the packed bed were analyzed. The simulation results show that the temperature of solid is higher than that of gas on the same height of the packed bed during the late stage of combustion， which reflects a good thermal storage capacity of the porous medium. The height difference of the fame surface between the tube wall and the center in the packed bed is much smaller than that in tube without porous media， which suggests that the flame is divided by the packed bed and then the uniformity and stability of the combustion within a porous medium are improved. References | Related Articles | Metrics

Mechanical Engineering

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Road Identification Method for Tracked Vehicles Based on System Response WANG Xin， GU Liang， LI Xiao-lei， DONG Ming-ming 2019, 40 (7):  968-973.  DOI: 10.12068/j.issn.1005-3026.2019.07.011 Abstract ( 710 )   HTML   PDF (2048KB) ( 885 )   In order to improve tracked vehicles’ adaptability to different types of road surfaces， a dynamic simulation model of tracked vehicles and various types of road was established based on the multi-body simulation platform. The time-domain dynamic response signals of vehicle centroid were collected through the driving simulation of tracked vehicles and road models， and the signals were decomposed by wavelet transformation. Distance evaluation technique was used to extract sensitive feature vectors. A road identification method based on the above sensitive feature vectors was proposed by using BP neural network. In order to verify the validity of the method， a test system based on small tracked vehicle models was built.The vehicle model drived on the actual road to collect the time-domain dynamic response signals of tracked vehicles′ body centroid， load wheels and track-terrain interaction. The results showed that the identification precision of the method is 99%. This method has a high identiciation ability for road types. References | Related Articles | Metrics

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Diagnosis of Gear Early Pitting Faults Using PSO Optimized Deep Neural Network LI Jia-lin， HE David， QU Yong-zhi 2019, 40 (7):  974-979.  DOI: 10.12068/j.issn.1005-3026.2019.07.012 Abstract ( 786 )   HTML   PDF (1432KB) ( 680 )   When gear faults were diagnosed based on the data-driven method， feature extraction was generally performed by Fourier transform， etc. The feature extraction method used has a great influence on the diagnosis results. Therefore， deep neural network(DNN) was proposed to diagnose early gear pitting faults and the vibration signals are directly used as the network inputs to avoid errors caused by feature extraction. In addition， the particle swarm optimization(PSO) algorithm was applied to optimize the DNN for obtaining a more stable training process and better diagnosis results. Principal component analysis(PCA) algorithm was used to reduce the dimensions of the DNN outputs. The data collected from the experiment was used to train and test the DNN. The fault diagnostic accuracy can reach over 90%， which proves that the proposed method is reasonably effective. References | Related Articles | Metrics

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Prediction of Cutting Forces in Gear Hobbing of Cylindrical Gears ZHANG Rong-chuang， LI Bai-chun， ZHANG Jing-qiang 2019, 40 (7):  980-985.  DOI: 10.12068/j.issn.1005-3026.2019.07.013 Abstract ( 779 )   HTML   PDF (1429KB) ( 893 )   The cutting forces involved during gear hobbing play an important role in process parameter optimization， hob wear prediction and hobbing machine design. The geometrical simulation of the gear hobbing process based on solid modelling was realized. Solid chips were extracted accurately and undeformed chip thickness was calculated. To model the hobbing process， the tool cutting edge was divided into small differential cutting edge segments. The cutting forces exerted on each cutting edge element were calculated based on Kienzle-Victor′s equations and the total force components acting on the hob were obtained by integrating the elementary force components. To validate the predictive model of gear cutting forces， the experiments were carried out in DMU50 five-axis CNC machining center equipped with a Kistler 9123C rotary dynamometer. The simulation results are compared with the experiments. The cutting process is well captured by the predictive model， and good correlations in cutting forces are observed between the predictions and experiments. References | Related Articles | Metrics

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Biomechanical Simulation of the Micro-dynamic Pedicle Screw LIU Chuang， LIU Qi， YAN Yun-hui 2019, 40 (7):  986-990.  DOI: 10.12068/j.issn.1005-3026.2019.07.014 Abstract ( 703 )   HTML   PDF (808KB) ( 787 )   By using the finite element method， the biomechanical performance of the micro-dynamic pedicle screw was evaluated. A three-dimensional finite element model of lumbar segments L3-L4 was reconstructed based on CT images of human spine. And on this basis， three kinds of L3-L4 fixed models: rigid fixation(M1)， micro-dynamic fixation(M2) and hybrid fixation(M3) were built to calculate the biomechanical parameters of surgical segments under the simulative physiological load. The simulation results showed that the micro-dynamic pedicle screw increases the range of motion(ROM) of the fixation segments in the direction of flexion and extension(95% in flexion and 83% in extension). The dynamic performance of the screw improves load transmitting between the lumbar motor units， and increases the normal physiological stimulation stress of the endplates by 4.25%~5.7%. Besides， the micro-dynamic fixation reduces the stress concentration effect on the implants， and the reduction of the pedicle screw stress is 9.2%~16.2% under flexion， extension and lateral bending conditions. References | Related Articles | Metrics

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Research on the Influencing Factors of Robot Milling Stability LIU Yu， HE Feng-xia 2019, 40 (7):  991-996.  DOI: 10.12068/j.issn.1005-3026.2019.07.015 Abstract ( 912 )   HTML   PDF (1448KB) ( 813 )   The robot milling is prone to modal coupling chatter， which will do damage to the tool and the robot body， resulting in a decrease in the positioning accuracy of the robot. In order to study the influencing factors of robot milling， a large number of experiments were carried out to study the effects of spindle speed， axial depth of cutting， feed rate， tool suspension length， up and down milling， and cutting materials on robot modal coupling chatter. The results showed that in a certain range， the lower the spindle speed， the faster the feed rate， the deeper the cutting depth， the shorter the suspension length， the up-milling， the harder the material， the more likely the modal coupling chatter occurs. The spindle speed and the tool suspension impact significantly on modal coupling chatter. References | Related Articles | Metrics

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Structural Design and Experimental Research of New Double-Folded Groove GE Jian-bing ， GONG Xian-sheng， PENG Xia， LIU Jin-jun 2019, 40 (7):  997-1002.  DOI: 10.12068/j.issn.1005-3026.2019.07.016 Abstract ( 791 )   HTML   PDF (525KB) ( 885 )   To ensure the stable transition of the multi-layer steel wire rope in the ultra-deep mine hoist， a new interlayer transition principle was proposed. The five-layer wire rope transition device was designed， and the range and method of the main structural parameters of the rope groove were analyzed. Based on the requirement for the stable transition of wire ropes， the twice spiral method of the central angle of the fold line was presented. The results showed that the optimal groove clearance is 0.03d~0.4d， and the groove depth is 0.3d~0.5d. The number of loops of the upper layer wire rope was twice more than that of the lower layer wire rope. The new multi-layer transition device reveals both multi-layer winding and neat arrangement of wire ropes， and the central angle of the fold line obtained by the twice spiral method can help the wire rope avoid sliding in the winding process. References | Related Articles | Metrics

Resources & Civil Engineering

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Effect of Modified Polyacrylamide on High Intensity Magnetic Separation of Hematite LI Wen-bo， ZHOU Li-bo， HAN Yue-xin， XU Hua-qiang 2019, 40 (7):  1002-1008.  DOI: 10.12068/j.issn.1005-3026.2019.07.017 Abstract ( 674 )   HTML   PDF (1708KB) ( 679 )   Based on the theory of flocculation-separation process， effects of modified polyacrylamide(HPM)dosage， pulp pH and stirring speed on high intensity magnetic separation of fine hematite ore were investigated by modified polyacrylamide(HPM) selective agglomeration pulp preparation-wet high intensity magnetic separation process. Scanning electron microscopy， EDS spectroscopy， Zeta potential and infrared spectrum measurements were used to study the micro-morphology of aggregates before and after magnetic separation and the change of surface properties of minerals after the action of reagents. The magnetic separation experimental results showed that， compared with the conventional high intensity magnetic separation， using selective agglomeration-high intensity magnetic separation process， the concentrate recovery of the presence of HPM in magnetic separation increases by 5.39% on condition that HPM dosage is 10g/t， pulp pH value is 10 and stirring speed is 954r/min. The apparent particle size of mineral particles in raw ore increases significantly after adding HPM and the recovery of fine hematite can be enhanced by high intensity magnetic separation with the presence of HPM. HPM can selectively flocculate hematite， and there are electrostatic adsorption and hydrogen bond adsorption on the surface of hematite， but there is no adsorption on the surface of quartz. References | Related Articles | Metrics

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Effect of Water Solubility of Serpentine on the Flotation of Brucite FU Ya-feng， SUN Hao-ran， YANG Yi-shen， YIN Wan-zhong 2019, 40 (7):  1009-1013.  DOI: 10.12068/j.issn.1005-3026.2019.07.018 Abstract ( 877 )   HTML   PDF (655KB) ( 684 )   Four kinds of serpentine with different grain size were selected， and the modified Hallimond tube was used to investigate the effect of conditioning time on the recovery of brucite and serpentine. By analyzing the properties of pulp pH， Mg2+ concentration， Zeta potential， contact angle and pulp viscosity， the water solubility of serpentine and its effect on the floatability of brucite by sodium oleate were systematically studied. The results showed that with the increase of conditioning time， the solubility of Mg2+ on serpentine surface increases gradually， resulting in reduction of serpentine Zeta potential. Furthermore， the oleate ion reacts easily with Mg2+ in solution to form magnesium oleate， so a large amount of oleate ion is consumed， resulting in a lower recovery rate of brucite. The finer the particle size of serpentine and the longer the conditioning time are， the greater the viscosity of the serpentine pulp is， which leads to the enhancement of foam stability during the flotation process， resulting in an increase in the foam entrainment rate of serpentine. References | Related Articles | Metrics

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Discussion on the Rationality and Experimental Research of the Ore-Drawing Ellipsoid Arrangement Theory TAN Bao-hui， ZHANG Zhi-gui， HE Rong-xing， ZHU Qiang 2019, 40 (7):  1014-1019.  DOI: 10.12068/j.issn.1005-3026.2019.07.019 Abstract ( 693 )   HTML   PDF (790KB) ( 819 )   The deficiencies of structural parameter design method based on ellipsoid arrangement theory were discussed and analyzed， involving whether the theory follows the consistence principle between the drawn-out ore body and the blasting ore body or not， whether the equivalence from drawn-out ore body tangent optimum principle to the draw off body of pure ore tangent optimum principle is reasonable， whether the viewpoint that the drawn-out ore body intersection results in ore dilution is scientific or not， and the rationality of the calculation formula of high sublevel structure. Three groups of physical drawing experiments with different structural parameters were designed and carried out. The experimental results showed that the ore recovery rate of large spacing structure parameter scheme is the lowest due to the drawn-out ore body and the blasting ore body seriously inconsistent. Both theoretical analysis and physical experiments showed that the design method of structural parameters of stope based on ellipsoid arrangement theory is unreasonable and needs to be further improved. References | Related Articles | Metrics

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Seismic Dynamic Response Analysis of Urban Underground Utility Tunnel Structure WANG Peng-yu， WANG Shu-hong， ZHU Cheng-jin 2019, 40 (7):  1020-1027.  DOI: 10.12068/j.issn.1005-3026.2019.07.020 Abstract ( 685 )   HTML   PDF (1121KB) ( 755 )   Seismic safety issues must be considered in the design of urban underground utility tunnel. Firstly， the reaction displacement method was used to calculate the internal force of the utility tunnel structure during the seismic， and the weak part of the utility tunnel was obtained. Then the dynamic time history method was used to analyze the seismic response of the utility tunnel， and the numerical model of the soil， structure was established， and the horizontal seismic action was input at the bottom of the model. The soil-structure interface contact unit was used， and the interaction between soil and structure was considered， and the separation and slip between the structure and the soil，the displacement deformation and stress distribution of the utility tunnel under horizontal seismic were obtained. The results show that the standard section structure of the underground utility tunnel has obvious lateral displacement under the action of horizontal seismic action， which is prone to bending and shear failure， but no obvious displacement in the horizontal direction. The weak link in the seismic damage of the utility tunnel structure is on the roof， the bottle plate and the side wall， as well as the wall end of the partition wall， and reinforcement measures are required in the seismic design. References | Related Articles | Metrics

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Experimental Study on Transverse Connection Method of the NSTS Structure LI Xue， WANG Lian-guang， YANG Jia 2019, 40 (7):  1028-1033.  DOI: 10.12068/j.issn.1005-3026.2019.07.021 Abstract ( 682 )   HTML   PDF (874KB) ( 635 )   A new steel tube slab(NSTS) structure using small-sized steel tubes as transverse connections was presented in order to ease the construction difficulty and enhance the transverse stiffness and the bearing capacity of the NSTS. Small-sized steel tubes were arranged between the longitudinal steel tubes in transverse direction， forming a composite structure of concrete-filled steel tube after concreting the longitudinal and transverse steel tubes. The connection methods between the transverse tube and the longitudinal tube were studied by analyzing the mechanical behavior of NSTS members. The results indicate that the bearing capacity of the specimen connected by bolts+T-shaped steel plate， and only by bolts is increased by 58.4% and 51.2% respectively， compared with that connected only by T-shaped steel plate， and the stiffness is increased by 123.3% and 97.5%， respectively. The connection method of bolts+T-shaped steel plate is most favorable to the mechanical behavior of the NSTS members. The concrete strength affects the stiffness and deflection of the specimen， but has little impact on the bearing capacity. References | Related Articles | Metrics

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Determination of Safety Integrity Level of Ammonia Refrigeration System LI Li， XU Kai-li， WANG Ben， YAO Xi-wen 2019, 40 (7):  1034-1038.  DOI: 10.12068/j.issn.1005-3026.2019.07.022 Abstract ( 788 )   HTML   PDF (395KB) ( 868 )   The risk probability reduction quotient(Q○rpr)is defined during the evaluation of the safety integrity level， and the formula of Q○rpr is given. Q○rpr is used to characterize the reduction in the risk probability. The value of the Q○rpr corresponds to the failure probability required by the system safety integrity level， and then can be used to determine the safety integrity level. Integrating the Q○rpr calculation into the classical HAZOP-LOPA evaluation method can more accurately and quickly evaluate the safety integrity level of the system. This method is used to evaluate the safety integrity level of the ammonia refrigeration system. The leakage and explosion accidents in the ammonia refrigeration system were analyzed， and the safety integrity level of the safety-related system was evaluated to verify the effectiveness and feasibility of the method. References | Related Articles | Metrics

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Landfill Leachate Treated Using Hybrid Anaerobic Baffled Reactor(HABR) CHANG Ming-dong， ZHU Tong， WANG You-zhao， SUN Zhi-cheng 2019, 40 (7):  1039-1044.  DOI: 10.12068/j.issn.1005-3026.2019.07.023 Abstract ( 761 )   HTML   PDF (887KB) ( 603 )   The disposal process of landfill leachate using hybrid anaerobic baffled reactor(HABR)was investigated to study the effect of temperature， HRT(hydraulic retention time) and ammonia concentration of inflow-water on reactor efficiency. The results showed that the chemical oxygen demand(COD)removal rate decreases by 49.11% when the temperature dropped from 30℃ to 10℃. With the shortening of HRT， the volume load increases gradually and the removal rate of COD shows a downward trend. When the influent concentration of ammonia nitrogen gradually increases， the removal capacity of COD in the reactor greatly decreases. Using the response surface method to get the optimal parameters showed that the removal rate of COD reaches the highest when the temperature is 34.97℃ and the HRT is 46.54h， the removal rate peaks at 88.57%. References | Related Articles | Metrics

Management Science

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Impact of Female Knowledge Workers′ Work-Family Enrichment on Stewardship Behavior—A Cross-Level Moderated Mediation Model ZHANG Lan-xia， ZHANG Liang-ting， WANG Ying 2019, 40 (7):  1045-1051.  DOI: 10.12068/j.issn.1005-3026.2019.07.024 Abstract ( 565 )   HTML   PDF (406KB) ( 573 )   Based on the survey questionnaire of 398 female knowledge workers from 112 teams， the role of psychological ownership in the transfer of work-family enrichment and employees， stewardship behavior was investigated， and the moderated mediation effect of interactional justice climate was analyzed. The results showed that work-family enrichment has significant positive impact on employees， stewardship behavior. Psychological ownership mediates the relationship between work-family enrichment and employees， stewardship behavior. The mediation effect of employees， psychological ownership between work-family enrichment and employees， stewardship behavior is higher under the condition of high interactional justice climate. References | Related Articles | Metrics

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Effect of Buyer Power on the Cost-Price Pass-Through ZHAO Qiu， LI Kai， TANG Chen-xi 2019, 40 (7):  1051-1055.  DOI: 10.12068/j.issn.1005-3026.2019.07.025 Abstract ( 661 )   HTML   PDF (337KB) ( 658 )   The influencing factors of cost-price pass-through in the vertical industry chain were studied. The cost-price pass-through was decomposed into the wholesale pass-through and retail pass-through， and the effect of buyer power on the two kinds of pass-through was analyzed under three vertical contracts: linear pricing， two-part tariffs， and revenue-sharing. The results showed that both buyer power and vertical contract will affect the pass-through. Under linear contract， buyer power has no influence on the retail pass-through， but has an impact on the wholesale pass-through， and the influence is related to the demand curvature. Under the two-part tariff system， the wholesale pass-through and retail pass-through have nothing to do with buyer power. Under revenue-sharing contract， the retail pass-through decreases in buyer power， and the wholesale pass-through increases in buyer power. References | Related Articles | Metrics

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Cognitive Experimental Research on Anti-sense Signs WANG Hai-ying， LI Ya-ning， ZHOU Chang， WANG Lin 2019, 40 (7):  1056-1060.  DOI: 10.12068/j.issn.1005-3026.2019.07.026 Abstract ( 658 )   HTML   PDF (446KB) ( 583 )   In real life， there are two kinds of signs which are similar in shape and opposite in meaning. In order to improve the recognition efficiency of such anti-sense signs， two typical anti-sense signs were selected to discuss the factors that affect the identification of this kind of signs， and the experimental research method was used to determine the significance and importance of the identification factors of anti-sense signs. The results show that the influencing factors are identified as the pattern distinctiveness， size， and color distinction of signs. Increasing the pattern distinctiveness of anti-sense signs can improve the recognition efficiency， but such distinctiveness is related to pattern difference. The size of signs has the most significant effect on the efficiency of anti-sense sign recognition. A reasonable distinction between the different colors of anti-sense signs can significantly improve the recognition efficiency. References | Related Articles | Metrics

Mathematics

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Study of Hilbert Curve Based on Moving Frame YU Yan-hua， LIU Ling， YANG Yun 2019, 40 (7):  1061-1064.  DOI: 10.12068/j.issn.1005-3026.2019.07.027 Abstract ( 612 )   HTML   PDF (619KB) ( 665 )   Most algorithms for describing three-dimensional Hilbert curves calculate node coordinates from the start point to the end point recursively. Directing at the multiple iteration， a new algorithm was brought forth. By means of constructing moving frame， the invariants under rigid body motion are obtained， that is， discrete curvature and torsion. Considering moving frame， the nodes are recoded. Establishing a map between the inflection point location number and the discrete curvature and torsion of the inflection point， based on that， writing the corresponding algorithm to make it for any number n， the pairs of curvature torsion and the image structure corresponding to the inflection points can be output. Compared to the algorithm Hilbert3(n)， the proposed algorithm is not limited to the order of the curve and does not depend on the iteration between the coordinates. Experimental results show that the algorithm is more efficient. References | Related Articles | Metrics