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15 December 2018, Volume 39 Issue 12 Previous Issue    Next Issue
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Information & Control
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Information & Control

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Novel Duty Ratio Modulation Strategy for PMSM DTC System YUAN Tian-qing， WANG Da-zhi， LI Ye， WANG Xing-yu 2018, 39 (12):  1673-1678.  DOI: 10.12068/j.issn.1005-3026.2018.12.001 Abstract ( 854 )   HTML   PDF (1112KB) ( 1041 )   In order to suppress the significant torque ripple and flux linkage ripple in CDTC(conventional direct torque control)-driven PMSM(permanent magnet synchronous motor)， and to reduce the calculations in conventional duty ratio modulation strategies， a novel duty ratio modulation strategy for PMSM DTC(direct torque control) system was proposed. The impact factors of torque and flux linkage ripples could be distinguished using the proposed strategy through the active angle between stator linkage and sector vector. A new switching table was designed to ensure the optimal choice of voltage vector. The simplified duty ratio calculation equations were obtained with the minimum calculations. Simulation and experimental results show that the novel modulation strategy can maintain the dynamic response in CDTC and suppress torque and flux linkage ripples efficiently. References | Related Articles | Metrics

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Job Shop Scheduling Problem with Limited Output Buffer ZENG Cheng-kuan， LIU Shi-xin 2018, 39 (12):  1679-1684.  DOI: 10.12068/j.issn.1005-3026.2018.12.002 Abstract ( 682 )   HTML   PDF (420KB) ( 1060 )   The job shop problem with limited output buffers(JS-LOB)was addressed with the objective of minimizing the process make-span. An integer nonlinear mathematical programming(INLP)model was proposed to describe this problem. Based on the model， a two-stage algorithm consisting of obtaining feasible solutions and a local search was proposed to solve the JS-LOB problem. The operator in local search was a neighborhood structure based on a disjunctive graph model. Computational results were presented for a set of benchmark tests， some of which were enlarged by different proportions between the capacity of the buffer and the number of jobs. The results show the effectiveness of the proposed algorithm through comparing with other exist algorithms and indicate when the processing time of the job conforms to a uniform distribution， and when the proportion between the capacity of the buffer and the number of jobs is larger than 20%， the influence of the buffer will become very small. References | Related Articles | Metrics

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Feature Adaptive Technology in Interactive Data Exploration Framework WANG Meng-xiang， LI Fang-fang， YU Ge 2018, 39 (12):  1685-1690.  DOI: 10.12068/j.issn.1005-3026.2018.12.003 Abstract ( 1013 )   HTML   PDF (704KB) ( 948 )   Interactive data exploration(IDE)is a key technique in a diverse set of discovery-based applications， which focuses on interaction， exploration and discovery and has a wide range of applications in many scenes and areas. The feature adaptive technology of interactive data exploration was studied in this paper with the background of massive academic literature data exploration. Firstly， a framework of interactive data exploration was presented， namely FA-IDE(feature-adaptive interactive data exploration) framework， which can dynamically adjust the subset of features during each iteration to meet the needs of the user′s interest diversity. Secondly， according to this framework， the evaluation criteria of the balance of feature subsets(BFS) were proposed in the stage of exploration and a sequence forward feature selection algorithm based on BFS was also given. Besides， for the phases of related sample discovery， a division level establishment method was proposed. According to the decision tree model which can divide the user interest area， a strategy of result set sorting based on similarity was proposed.The results of experiments show that the accuracy and efficiency of the proposed method have been effectively improved. References | Related Articles | Metrics

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Multi-layer Nested Database Encryption Scheme for Multiple Users ZHOU Fu-cai， ZHANG Xin-yue， ZENG Kang， QIN Shi-yue 2018, 39 (12):  1691-1696.  DOI: 10.12068/j.issn.1005-3026.2018.12.004 Abstract ( 668 )   HTML   PDF (590KB) ( 705 )   Encrypted database scheme about outsourced data confidentiality and user privacy was researched， and a scheme of multi-layer nested database encryption for multiple users was proposed. A data encryption scheme was also proposed based on onion model to perform nested encryption on outsourced data by applying multi-layer theory with a variety of data encryption algorithms to guarantee data confidentiality and to work with SQL queries in different types. Meanwhile， user privacy protection scheme was proposed based on single server private information retrieval(PIR)to enable users to send SQL queries with sensitive data and protect the privacy of users when accessing the database， realizing user anonymous query. The security analysis results show that the scheme protects data confidentiality and user privacy. An evaluation result tested with a benchmark tool Sysbench demonstrates its well query processing efficiency， throughput and robustness. References | Related Articles | Metrics

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A Judgment Method of Athlete′s Movement State Based on Pulse Wave Mathematical Model SHI Han， ZHAO Hai， CHEN Xing-chi， LI Da-zhou 2018, 39 (12):  1697-1701.  DOI: 10.12068/j.issn.1005-3026.2018.12.005 Abstract ( 756 )   HTML   PDF (518KB) ( 918 )   Aiming at the problem that the athlete′s pulse wave information is used to determine the motion state(high intensity motion or calm)and reduce the randomness of the body condition to the pulse wave characteristic information， a method to construct the original pulse wave signal was presented. The method of training-test was used to classify the athletes′ heart rate to analyze the athletic state of the athletes and assist them in carrying out sports training work. Through the training of 10 athlete volunteers in different states， the original signal of the pretreatment was modeled and the physiological information was extracted. The SVM was used to supervise the training and test. The results show that the method can effectively discriminate the athlete′s heart rate state and get the state of motion. References | Related Articles | Metrics

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Influence of Coronary Artery Stenosis on Transfer Function Between Peripheral and Central Arteries ZHANG Liang-yu， BIAN Tian-yuan， XU Li-sheng 2018, 39 (12):  1702-1707.  DOI: 10.12068/j.issn.1005-3026.2018.12.006 Abstract ( 665 )   HTML   PDF (447KB) ( 751 )   To observe the changes of central artery wave and explore the correlation between transfer function of peripheral and central artery and coronary artery stenosis in patients. Center artery and radial artery pulse wave before and after stent surgery from 9 patients with coronary artery stenosis were collected. ARX(auto-regressive with extra inputs) transfer function before and after stent surgery were established. Radial artery waveform after surgery was reconstructed with the transfer function model before and after surgery. Characteristic points of the two central arterial waveforms were extracted and the characteristic parameters K and t of the reconstructed two central arterial pressure were calculated. And then， the significant difference analysis of the measured central arterial pressure parameters was analyzed. The experimental results indicated that coronary artery stenosis has a certain impact on the transfer function， and clinical significance of the acute myocardial infarction in patients with acute illness cannot be reconstructed with a common transfer function of the central artery. References | Related Articles | Metrics

Materials & Metallurgy

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Carbide Precipitation in Ferrite in Nb-V-Bearing Low-carbon Steel During Isothermal Quenching Process LI Xiao-lin， DENG Xiang-tao， LI Yan-mei， WANG Zhao-dong 2018, 39 (12):  1708-1712.  DOI: 10.12068/j.issn.1005-3026.2018.12.007 Abstract ( 935 )   HTML   PDF (3708KB) ( 791 )   Precipitation behavior of carbides in Nb-V HSLA steel during isothermal quenching process and its strengthening effect were studied using TEM and nanoindentation tests. The results indicated that interphase precipitations and dispersed precipitations could occur simultaneously in the specimen treated at 700℃ for 60min， while in other specimens， only random precipitations were observed. This phenomenon can be explained by mass balance criterion and ledge mechanism during diffusional phase transformation. It was also found that the average hardness of the specimen held at 600℃ for 20min was 3.87GPa and was 4.10GPa at 650℃ for 20min. Moreover， the TEM results illustrated that carbide precipitations in the specimen holding at 650℃ for 20min were dispersed more uniformly and the volume fraction of the precipitations was greater than that treated at 600℃ for 20min. The strengthening contributed by the precipitations was 110MPa in the specimen treated at 650℃ for 20min， evaluated by the Ashby-Orowan mechanism. References | Related Articles | Metrics

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Bending Fatigue Property of Low-C Medium-Mn Steel with High Strength and Toughness QI Xiang-yu， DONG Ying， HU Jun， DU Lin-xiu 2018, 39 (12):  1712-1716.  DOI: 10.12068/j.issn.1005-3026.2018.12.008 Abstract ( 1010 )   HTML   PDF (2580KB) ( 841 )   The three-point-bending fatigue property of low-C medium-Mn steel was studied by GPS-100 fatigue testing machine， where the S-N curve was plotted and the characteristics of fatigue fracture surface were analyzed. The effect of transformation induced plasiticity(TRIP)on fatigue property of the steel was also investigated. The results showed that the fatigue strength of the tested sample was about 1006MPa and the fatigue ratio was 1.20. The fatigue crack was originated from the corners in the lower surface of the sample. There were a large number of secondary cracks in the crack propagation zone， which could reduce the propagation rate effectively and improve fatigue strength of the steel. The fracture type was ductile for the axial dimples and elongated dimples were observed in the transient fracture zone. Furthermore， the excellent fatigue property of this steel was mainly attributed to the TRIP effect of retained austenite in the small plastic deformation zone in front of the fatigue crack， which could absorb a large amount of strain energy， blunt crack and reduce the crack propagation rate. References | Related Articles | Metrics

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Bending Force Prediction Model in Hot Strip Rolling Based on Artificial Neural Network Optimize by Genetic Algorithm WANG Zhen-hua， GONG Dian-yao， LI Guang-tao， ZHANG Dian-hua 2018, 39 (12):  1717-1722.  DOI: 10.12068/j.issn.1005-3026.2018.12.009 Abstract ( 607 )   HTML   PDF (944KB) ( 738 )   In view of the drawbacks of the traditional bending force preset model and the characteristics of hot strip rolling， a bending force prediction model is built based on genetic algorithm(GA)and artificial neural network(ANN)and the prediction is carried out on the end stand of finishing mill using a large amount of production data from 1580mm hot rolling line in a steel corp. The features of the model are as follows: a large number of actual data is used as input for the ANN training， the influence of various input parameters are fully considered， the framework of the model is relatively simple and easy to implement， and the overall performance is evaluated by the mean absolute percentage error， root mean square error and correlation coefficient. By comparing the predicted results with the experimental ones， the prediction accuracy of the model is verified. It shows that the GA-ANN prediction model of roll bending force can realize a high nonlinear fitting， which is suitable for improving the accuracy to control head shape of hot strip rolling. This study provides guidance and test foundation for the actual bending force setting. References | Related Articles | Metrics

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Effect of Semi-solid Isothermal Heat Treatment on Microstructure of 7075 Alloy ZHU Cheng， LUO Zhou-mei， WANG Rui， ZHAO Zhi-hao 2018, 39 (12):  1723-1726.  DOI: 10.12068/j.issn.1005-3026.2018.12.010 Abstract ( 688 )   HTML   PDF (3946KB) ( 719 )   Microstructure evolution of 7075 alloy from dendrite to non-dendrite during semi-solid isothermal heat treatment was studied and the difference of the phase constituents between as-cast and semi-solid microstructure was also investigated. The results show that the formation of non-dendritic structures has three stages: the disappearance of branching characteristics， flattening grain boundaries， arcuating grain boundary and grain growth. The disappearance of branching characteristics is caused by the melt of the low-melting-temperature phases located in the secondary dendrite arm: the agglomeration of part liquid phase wrapped inside the solid particles， some liquid phase flowed from the dendrite channels to the grain boundaries and the other liquid phase lapped together to form new solid particles. The phase constituents of both as-cast and semi-solid microstructures in 7075 alloys are all α-Al， η(MgZn2) and θ(Al2Cu). References | Related Articles | Metrics

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Water Model Study on Gas-Liquid Reaction Process of Desulfurization of Molten Iron with Magnesium Vapor WANG Kun， LIU Yan， HOU Jun-yang， ZHANG Ting-an 2018, 39 (12):  1727-1731.  DOI: 10.12068/j.issn.1005-3026.2018.12.011 Abstract ( 663 )   HTML   PDF (705KB) ( 605 )   For the gas-liquid reaction process of desulfurization of molten iron with magnesium vapor， the physical simulation method was used to study on the reaction process of desulfurization of molten iron. The high speed camera was used to obtain bubble dispersion phenomena under the conditions of different injection modes， gas flow rates and impeller immersion depth. The first order reaction of NaOH with CO2 was used to simulate the absorption rate and utilization rate of magnesium vapor in the process of desulfurization. Results show that: under the conditions of centric bottom blowing injection mode， the gas flow rate 2.0m3/h， impeller immersion depth 250mm， the bubble refinement and dispersion in the bath was good. The gas-liquid mass transfer rate and utilization rate of CO2 bubbles were observably improved. References | Related Articles | Metrics

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Effect of Reaction Heat per Unit Mass on Preparation of Ferrotitanium by Thermite Method CHENG Chu， DOU Zhi-he， ZHANG Ting-an， SU Jian-ming 2018, 39 (12):  1732-1736.  DOI: 10.12068/j.issn.1005-3026.2018.12.012 Abstract ( 588 )   HTML   PDF (2204KB) ( 768 )   Effect of reaction heat per unit mass on the ferrotitanium prepared by thermite method was studied. The samples were analyzed by scanning electron microscope， energy spectrum analyzer， oxygen/nitrogen/hydrogen analyzer and inductively coupled plasma emission spectrometer. The results indicate that the burn rate of the ingredients gradually increases with the increasing reaction heat per unit mass， while it decreases with the increasing Ti content of the objective ferrotitanium. Meanwhile， when the reaction heat per unit mass increases， the Al and O contents of the alloy decrease. A higher reaction heat per unit mass is beneficial to the removal of Al2O3 inclusion because of a better slag-metal separation. Nevertheless， under the same reaction heat， the effect of slag-metal separation goes worse and Al and O contents increase with the increasing Ti content of the objective ferrotitanium. Reaction heat per unit mass has a greater effect on the burn rate， slag-metal separation and the recovery of objective ferrotitanium with high Ti content. References | Related Articles | Metrics

Mechanical Engineering

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Natural Characteristics Analysis and Validation of Fiber Metal Laminates Thin Plates Under Cantilever Boundary XU Zhuo， LI Hui， XUE Peng-cheng， WEN Bang-chun 2018, 39 (12):  1737-1742.  DOI: 10.12068/j.issn.1005-3026.2018.12.013 Abstract ( 563 )   HTML   PDF (707KB) ( 648 )   The natural characteristics of fiber metal laminates(FMLs)thin plates under cantilever boundary were calculated and validated by combining theory with experiment. According to the structural characteristics of FMLs thin plates， theoretical modeling was carried out based on the mechanics of composite material and classical laminated plate theory. Then， the natural characteristics were solved by using the orthogonal polynomial method. Meanwhile， the calculation processes were proposed. A natural characteristic experiment system of FMLs thin plates was established and the natural characteristics of a TA2/TC500 FMLs thin plate were acquired. It is found that comparing the calculation results of the frequencies with the test ones， the errors are within the range of 1.2% and 4.7%， and the trends of modal shapes are consistent as well， thus the effectiveness of the above method is verified. References | Related Articles | Metrics

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Static Hysteresis Behavior Analysis and Stiffness and Damping Identification of Bolted Joints SUN Wei， TAN Long-fei， WU Ning-xiang 2018, 39 (12):  1743-1747.  DOI: 10.12068/j.issn.1005-3026.2018.12.014 Abstract ( 854 )   HTML   PDF (898KB) ( 857 )   Obtaining the static hysteresis behavior of bolted joints and identifying their stiffness and damping are of great significance for the design of bolt joints and the formulation of the assembly process. A three-dimensional finite element model is used to predict the hysteresis characteristics of bolted joints， and the setting method of the bolt contact parameters is given. Finally， a simple example of the bolted lap beam is chosen to present the developed method. The rationality of the finite element model of the bolted lap beam and the obtained hysteresis loop are validated by experiments. The time-varying stiffness， mean stiffness and loss factor of the bolted joint are identified by the obtained hysteresis loop. The results show that the stiffness of the bolted joint increases and the loss factor(damping parameter)decreases with the increase of the preload force. References | Related Articles | Metrics

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Research on Pose Modeling and Precise Assembly Method for Large Cylinder-Tail Nozzles HUANG Lei， HOU Zeng-xuan 2018, 39 (12):  1748-1753.  DOI: 10.12068/j.issn.1005-3026.2018.12.015 Abstract ( 640 )   HTML   PDF (935KB) ( 746 )   According to the setting and safety of docking assembly for large cylinder-tail nozzles， a new method for precise docking assembly is proposed based on LD-PSD to improve the assembly accuracy and efficiency. First， the calibration block marker coordinates are obtained by using laser trackers， and the least square model is established according to the deviation between theoretical coordinate and the measured coordinate of the mark point. Precise spatial registration is implemented between measured coordinate and global coordinate by using singular value decomposition(SVD). Then， the tracking instrument is used to obtain the coordinate of the key point of the nozzle and cylinder. The mathematical model of the current position of nozzle cylinder is established using the least squares and HSF. 6-DOF CNC equipment is developed， and taking the posture of the cylinder as a reference， posture preconditioning is done by the anti-solution of nozzle pose parameters. The online feedback system is launched to detect the pre-assembly error. By planning micro rotation and micro translational path， the position of the nozzle is corrected several times to meet the requirement of a given assembly accuracy. The test results in a power plant show that the assembly process is smooth and efficient， and it can realize the precise docking assembly of large cylinder-tail nozzles. References | Related Articles | Metrics

Resources & Civil Engineering

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Test on Fluidized Magnetization Roasting of Donganshan Carbonate-Bearing Iron Ore YU Jian-wen， HAN Yue-xin， LI Yan-jun， CHU Man-sheng 2018, 39 (12):  1754-1758.  DOI: 10.12068/j.issn.1005-3026.2018.12.016 Abstract ( 655 )   HTML   PDF (681KB) ( 688 )   A pilot-scale fluidized magnetization roasting reactor was introduced and used to study the effects of roasting temperature， flow rates of reducing gas CO and fluidizing gas N2 on magnetization roasting performance of the pre-concentrate from Donganshan iron ore. The results show that a high-grade ground magnetic concentrate of 66.1% iron with an iron recovery of 91.2% can be obtained from the pre-concentrate after roasting at 540℃ with a gas mixture of CO 4m3/h and N2 2m3/h. The iron chemical phase， optical microstructure， and Mossbauer spectrum analyses indicate that weakly magnetic siderite and hematite can be converted to ferromagnetic magnetite successfully. The coarse hematite particles(＞100μm) partly transformed into magnetite， while such particles with a Fe2O3@Fe3O4 core-shell structure can also be effectively recovered by subsequent magnetic separation after liberating from gangue minerals due to their strong magnetism. References | Related Articles | Metrics

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Oxidation Kinetics of Magnetite During the Cooling Process of Magnetization Roasting SUN Yong-sheng， CAO Yue， HAN Yue-xin， LI Yan-jun 2018, 39 (12):  1759-1763.  DOI: 10.12068/j.issn.1005-3026.2018.12.017 Abstract ( 723 )   HTML   PDF (703KB) ( 816 )   The cooling process of magnetization roasting has been investigated. The variation of magnetite oxidation reaction fraction and rate was observed， and the oxidation kinetics was analyzed using model matching method. The results indicated that oxidation temperature had a significant effect on the reaction fraction and rate. At the same oxidation time， the reaction fraction and rate increased as temperature increasing. The curves of reaction fraction and rate under different temperatures presented the similar variation with increasing reaction time. The mechanism function of isothermal oxidation of magnetite was determined to be Avrami-Erofee equation with n=4. The apparent activation energy and pre-exponential factor were 135.2kJ·mol and 6.19×1010min-1， respectively. References | Related Articles | Metrics

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Study on Seismic Response of Silo-Stock-Foundation Interaction System LI Shu-wei， ZHAO Wen， GUO Zhi-yu 2018, 39 (12):  1764-1768.  DOI: 10.12068/j.issn.1005-3026.2018.12.018 Abstract ( 657 )   HTML   PDF (1356KB) ( 734 )   In order to reveal the mutual response of silo-stock-foundation system under dynamic action， a small vibration table silo test was carried out. The rules of acceleration， displacement and earth pressure of the silo composite structure under seismic load were studied， and the seismic response of silo-stock-foundation interaction system was analyzed by numerical simulation. Results show that: The peak acceleration of the silo top has a tendency to increase first and then decrease with the increase of the storage material. The relative movement of the storage material and the silo has a shock absorption effect on the silo system. The displacement patterns on the busbar of the same working condition are similar， and the displacement peak increases with the increase of the storage amount， and the difference between the upper and lower sides is larger. Under the action of seismic waves， the earth pressure fluctuates up and down， but the overall trend shows a gradual increase until it stabilizes at a certain value. The research can provide some theoretical basis and reference values for the safe operation of silo structure under earthquake actions. References | Related Articles | Metrics

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NO2 Gas Sensor Based on NiO Nanofilms ZHAO Si-kai， ZHONG Xiang-xi， ZHOU Peng-fei， SHEN Yan-bai 2018, 39 (12):  1769-1773.  DOI: 10.12068/j.issn.1005-3026.2018.12.019 Abstract ( 680 )   HTML   PDF (1818KB) ( 821 )   NiO nanofilms were synthesized by sol-gel dip-coating method using the mixture of NiC4H6O4·4H2O， NH3·H2O and C3H8O as the precursor. The effects of pulling speed and coating layer on the morphology， structure and NO2 sensing properties of NiO nanofilms were investigated. Uniform and porous NiO nanofilms were obtained under the preparation conditions of pulling speed of 400μm/s and coating layer of 2. The films were composed of cubic nanocrystalline NiO particles with the diameter of 20~30nm. NO2 sensing measurements demonstrated that NiO nanofilms with p-type semiconductor characteristic show good response-recovery properties as well as excellent reversibility. NO2 sensing mechanism of NiO nanofilms was investigated and discussed. References | Related Articles | Metrics

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An Improved Automatic Algorithm of Acoustic Emission P-Wave Arrival Time Picking LIU Fei-yue， YANG Tian-hong， DENG Wen-xue， ZHANG Peng-hai 2018, 39 (12):  1774-1778.  DOI: 10.12068/j.issn.1005-3026.2018.12.020 Abstract ( 637 )   HTML   PDF (801KB) ( 807 )   Acoustic emission(AE)monitoring technique has been widely applied in the area of geotechnical engineering. Automated arrival time picking of P-wave is the fundament and key in the further rock mechanical AE study. In order to get the more accurate arrival time of AE single， an improved Pphase-Picker P-wave arrival time picking algorithm was proposed and its principle was described in detail. Several automatic arrival time picking algorithm were compared in 1000 typical AE wave， the result indicated that the improved algorithm can not only get a more accurate P-wave arrival time rapidly， but also can get an error estimation of P-wave arrival time. References | Related Articles | Metrics

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Zircon U-Pb Dating and Petrogenesis of Volcanic Rocks in Hadataolegai Formation， Middle Great Xing’an Range SI Qiu-liang， WANG En-de， TANG Zhen， MA Yong-fei 2018, 39 (12):  1779-1782.  DOI: 10.12068/j.issn.1005-3026.2018.12.021 Abstract ( 626 )   HTML   PDF (637KB) ( 782 )   Zircon U-Pb isotopic dating and geochemical analysis were used to study the formation age and petrogenesis of the volcanic rocks in Hadataolegai Formation， the middle Great Xing’an Range. LA-ICP-MS dating results show that the volcanic rocks in Hadataolegai Formation formed in Middle Triassic from 234Ma to 244Ma. The geochemical study suggests that the volcanic rocks are poor in silicon，rich in alkalis， calcium and magnesium. The total RE amount ranges from 122.32×10-6 to 140.66×10-6. Fractionation of LRE and HRE is obvious［m(La)/m(Yb)N=11.99~18.68］ and Eu has no anomalies (δEu=0.84~0.98). The trace element geochemistry are characterized evidently by enrichment of Rb， K， Ba， Th， and depletion of Nb， P， Ti. Original magma of the volcanic in Hadataolegai Formation is chiefly derived from enriched lithospheric mantle， and contaminated by crustal material. References | Related Articles | Metrics

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Influence of Acid and Alkali Modified Fly Ash on Handling Ammonia Nitrogen Wastewater by SBR Reactor LIN Xin， LIU Fang， HU Xiao-min 2018, 39 (12):  1783-1787.  DOI: 10.12068/j.issn.1005-3026.2018.12.022 Abstract ( 707 )   HTML   PDF (848KB) ( 624 )   The fly ash was acid or alkali modified with 1mol/L hydrochloric acid and 1mol/L NaOH solution. The modified and non-modified fly ash were added into the SBR reactor for simulating the treatment of ammonia nitrogen wastewater. The bacteria in the reactor were taken from the activated sludge of a biochemical pool in a sewage treatment plant. The concentration of the influent NH+4-N was increased gradually. Then， the concentration of NH+4-N in the effluent of the reactor， the sludge concentration and the abundance of the dominant bacteria were all measured. The experimental results show that after the reactors has run for 40 days with an influent NH+4-N concentration of 861.1mg/L， the removal rate of NH+4-N of R3 reactor(adding acid-base modified fly ash)， R2 reactor(adding unmodified fly ash) and R1 reactor(without adding fly ash) are 100%， 98.76% and 91.87%， respectively. If the concentration of sludge in the three reactors is indirectly characterized by protein concentration， the concentration of protein in the R3 reactor， R2 reactor and R1 reactor are 829.08mg/L， 789.37mg/L and 154.2mg/L， respectively. In addition， the high throughput sequencing results show that the abundance of nitrifying bacteria and nitrifying bacteria in R3 reactor is higher than that in R1 and R2 reactor. References | Related Articles | Metrics

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Numerical Simulation and Analytical Study on Mechanical Behavior of Cast-in-Place Utility Tunnel Joint WANG Peng-yu， WANG Shu-hong， JIERULA Alipujiang， LIU Wei-hua 2018, 39 (12):  1788-1793.  DOI: 10.12068/j.issn.1005-3026.2018.12.023 Abstract ( 580 )   HTML   PDF (937KB) ( 762 )   The bell and spigot joint is the common structure form of the utility tunnel joint， and its mechanical properties and failure modes are very important for engineering design and construction. First， a numerical model for soil and underground utility tunnel was established by using nonlinear finite element software ABAQUS; then， the utility tunnel was divided into physical unit elements and the stress distribution and the deformation law of the soil and the utility tunnel were studied by extracting the deformation amount and the stress value of the nodes at the joint; finally， the ductility coefficient and the cracking load of the utility tunnel were calculated. Through numerical simulation and theoretical calculation， the potential safety hazards and damage patterns of the joints in the tube gallery were obtained to provide some theoretical references for waterproofing and uneven settlement control. References | Related Articles | Metrics

Management Science

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Kansei Knowledge Acquisition Based on the Improved Variable Precision Bayesian Rough Set HU Ming-cai， GUO Fu， YE Guo-quan 2018, 39 (12):  1794-1799.  DOI: 10.12068/j.issn.1005-3026.2018.12.024 Abstract ( 543 )   HTML   PDF (394KB) ( 674 )   The variable precision Bayesian rough set(VPBRS)approach is a flexible method for Kansei knowledge acquisition to accommodate the individual differences within a user group. In order to handle the possible combinatorial explosion at the stage of Kansei rule extraction， an improved algorithm based on sequential covering strategy is proposed. Basically， the approximation regions of Kansei decision classes are taken as the input， and the selection of conjunctive items with maximum covering ability is taken as the greedy search strategy for rule specialization. On this basis， the approximation region is covered step by step through iterative learning， and the decision rule set is extracted. A basic example and a design example of toaster appearance are conducted， whose results show that the improved VPBRS approach is effective. References | Related Articles | Metrics

化学

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Preparation and Investigation of PVDF Strengthened Imidazole Functionalized Poly(Aryl Ether Ketone) Membranes YANG Jing-shuai， WANG Yi-han， ZHAN Si-fan， YANG Guo-hao 2018, 39 (12):  1800-1804.  DOI: 10.12068/j.issn.1005-3026.2018.12.025 Abstract ( 684 )   HTML   PDF (660KB) ( 720 )   Novel polymer electrolyte membranes of thermostability with superior conductivity and improved dimensional stability have been proposed based on poly(vinylidene fluoride)(PVDF)blended with methylimidazolium poly(aryl ether ketone)(MeIm-PAEK). The relationship between the properties and chemical components of membranes has been investigated. 1H NMR spectra have confirmed the successful reaction of the imidazole function. Acid doping measurement indicates that grafting imidazole groups into PAEK makes the PAEK absorb phosphoric acid and the acid doping content increase with the increase of imidazole groups’ grafting degree. The dimensional stability of MeIm-PAEK membranes in the concentrated phosphoric acid solution under elevated temperatures can be improved by blending PVDF. The 70MeIm-PAEK/PVDF membrane achieves an acid doping content of 226% and volume swelling of 248% after being immersed in the 85% phosphoric acid solution. This acid doped membrane exhibits a conductivity as high as 0.141S/cm at 180℃ without humidifying. References | Related Articles | Metrics