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15 August 2018, Volume 39 Issue 8 Previous Issue    Next Issue
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Information & Control
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Information & Control

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Fiber Bragg Grating Multi-level Strain Sensor Based on the Structure of Extendable Rod ZHAO Yong， HE Wen-zheng， TANG Yong-chao 2018, 39 (8):  1065-1069.  DOI: 10.12068/j.issn.1005-3026.2018.08.001 Abstract ( 657 )   HTML   PDF (863KB) ( 624 )   In order to expand the measurement range of optical fiber grating load cell and improve the measurement accuracy of the sensor， a novel multi-level load cell was designed theoretically and simulated by Matlab. Simulation result showed that the single sensor had good linearity when the fluctuation of wavelength is below 0.2nm. In this system， the dual-optical fiber gratings were connected in series with the upper and lower sides of the equal-strength beam. And the output signal of the optical fiber grating was demodulated by the method of light intensity demodulation. By the extendable rod structure， the sensor becomes multi-level sensing， then the measurement range was broadened unchanging its measurement resolution. The feasibility of the proposed sensor was verified by experimental results. References | Related Articles | Metrics

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Double Integral Indirect Sliding Mode Control for Phase-Shifted Full-Bridge Converters WANG Da-zhi， GAO Ming， LI Zhao 2018, 39 (8):  1069-1074.  DOI: 10.12068/j.issn.1005-3026.2018.08.002 Abstract ( 708 )   HTML   PDF (1286KB) ( 663 )   A double integral indirect sliding mode control strategy was proposed for phase-shifted full-bridge (PSFB) DC-DC converters to improve the output performance. The theoretical analysis of motion of sliding mode controlled system was done according to Lie derivative method. The order reduction in the process of indirect sliding mode controlling was analyzed. The existence region of sliding mode and sliding motion were described in three-dimensional phase space. The selection basis of the sliding surface coefficients was given. Experimental results show that the proposed control strategy can improve the robustness and dynamic quality of PSFB， and eliminate state errors in the output， based on the fortes of sliding mode control. References | Related Articles | Metrics

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Sound Source Localization Technology Based on Generalized Cross-Power Spectrum Phase ZHANG Chuan-yi， LU Xiao 2018, 39 (8):  1075-1079.  DOI: 10.12068/j.issn.1005-3026.2018.08.003 Abstract ( 908 )   HTML   PDF (592KB) ( 727 )   The paper mainly researches how to improve sound source localization effects in indoor environments with complex noise and serious reverberation. Firstly， the signal model of the indoor microphone array is analyzed and a suitable array topology is established. Secondly， a lot of parameters of the filter in the cepstral domain are determined optimally by simulation. Then， the generalized cross-power spectrum phase is proposed to make the peak value more obvious. In addition， many weight functions are simulated and compared in Matlab to further improve the accuracy of sound source localization. Finally， the proposed algorithm is verified. The result shows that the localization success rate is up to 80% when the angle error and distance error of the improved algorithm are ±10°and ±15cm， respectively. References | Related Articles | Metrics

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Environment-Friendly Optimized Gateway Deployment for Underwater Acoustic Sensor Networks JIN Zhi-gang， WANG Ning， WU Jing-jing， SU Yi-shan 2018, 39 (8):  1080-1085.  DOI: 10.12068/j.issn.1005-3026.2018.08.004 Abstract ( 613 )   HTML   PDF (636KB) ( 576 )   A novel environment-friendly optimized gateway deployment for underwater acoustic sensor networks is proposed to overcome the problem of increased end-to-end delay and decreased packet delivery rate caused by marine mammals sharing the acoustic channel with underwater acoustic sensor networks. Gateways are considered as data centers of underwater acoustic sensor networks and the location of marine mammals is determined with statistical methods. The interference region of mammals-gateway is determined through combining the location with the radius of interference calculated by acoustic channel model. The strategy utilizes integer linear programming and greedy-exchange heuristic algorithm to realize the minimization of the average end-to-end delay. Simulation results and comparisons with the random deployment and the deployment ignoring mammals show that the new proposed gateway deployment strategy decreases the end-to-end delay by 62% and 52% and increases the packet delivery rate by 36% and 19%. References | Related Articles | Metrics

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An Efficient and Secure Cloud Storage Scheme with Hidden Access Patterns LI Yu-xi， ZHOU Fu-cai， XU Zi-feng 2018, 39 (8):  1086-1091.  DOI: 10.12068/j.issn.1005-3026.2018.08.005 Abstract ( 716 )   HTML   PDF (506KB) ( 639 )   Aiming at the problems of data confidentiality and user’s privacy leakage in cloud， this paper proposes an efficient and secure cloud storage scheme with hidden access patterns. Firstly， the files are divided into data blocks with fixed sizes， and encrypted by pseudo-random functions and collision-resistant Hash functions. Then， in order to construct the secure cloud storage structure， the blocks are uploaded into pseudo-random collection superset in the cloud server. Meanwhile， a two-round access strategy that hides the access patterns， reduces the storage cost and access interaction is designed. Security analysis shows that the proposed scheme achieves L1L2-dynamic adaptive security. Experimental results show that the proposed scheme can not only protect data confidentiality， but also be more suitable for the actual cloud storage. References | Related Articles | Metrics

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Searchable Encryption for Graph Data with Adjacency Query XU Zi-feng， ZHOU Fu-cai， LI Yu-xi， QIN Shi-yue 2018, 39 (8):  1092-1097.  DOI: 10.12068/j.issn.1005-3026.2018.08.006 Abstract ( 845 )   HTML   PDF (392KB) ( 677 )   This paper proposes a searchable encryption model for graph data to address the problem that most of the current searchable encryption schemes cannot deal with complex data structures. The algorithms and security models of the scheme are described. Taking the encryption index of matrix structure into account， the detailed description of the searchable encryption scheme for graph data that supports adjacency queries is presented. The scheme utilizes pseudo-random functions and pseudo-random permutations to protect the privacy of the graph data and the encrypted index. Real models and ideal models test the security of the scheme. Compared with traditional searchable encryption schemes， the proposed scheme has more flexible searching ability and higher efficiency， which promotes broader application under big data environment. References | Related Articles | Metrics

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A Publicly Verifiable Outsourced Database Scheme with Full Operations WANG Qiang， XUAN Peng-kai， WANG Hong-wei， ZHOU Fu-cai 2018, 39 (8):  1098-1103.  DOI: 10.12068/j.issn.1005-3026.2018.08.007 Abstract ( 651 )   HTML   PDF (399KB) ( 633 )   Aiming at the existing shortcomings of outsourced database schemes including heavy temporal and spatial cost， low efficiency for query and update， and lack of the support for the complete verification of multiple SQL query results， this paper proposes a publicly verifiable outsourced database model supporting full operations. The formal definition and security definition are presented. On the basis of the model， a publicly verifiable outsourced database scheme， composed of three entities， is constructed using bilinear mapping accumulator and authenticated skip list. Also， the implement and the communication are described in detail. Finally， the security and efficiency are analyzed， respectively， which shows that the proposed scheme is with unforgeability and high efficiency. References | Related Articles | Metrics

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Recommendation Algorithm Based on Community Detection in Bipartite Networks CHEN Dong-ming， YAN Yan-bin， HUANG Xin-yu， WANG Dong-qi 2018, 39 (8):  1103-1107.  DOI: 10.12068/j.issn.1005-3026.2018.08.008 Abstract ( 992 )   HTML   PDF (458KB) ( 824 )   The efficiency of traditional user-based collaborative filtering (user-based CF) recommendation algorithm is reduced with data increasing. This paper proposes a recommendation algorithm based on community detection (RACD) in bipartite networks by introducing bipartite network community detection theory into user-based CF recommendation algorithm. Firstly， the user-item rating matrix is mapped into user-item bipartite network. Then， the community information of each user is obtained by using RACD to divide the user-item network. Finally， the items are recommended to the target user according to other users in the same community. Experiments on real-world classic network datasets show that the RACD can effectively improve real-time recommendation efficiency of the recommendation system. References | Related Articles | Metrics

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Underdetermined Blind Separation Based on Improved EMD Algorithm JI Ce， SUN Meng-xue， ZHANG Jun 2018, 39 (8):  1108-1113.  DOI: 10.12068/j.issn.1005-3026.2018.08.009 Abstract ( 761 )   HTML   PDF (1043KB) ( 709 )   In order to improve the effect of data fitting， a method of extremum extension on endpoints is proposed， which is aimed at the endpoint effect of empirical mode decomposition (EMD) algorithm. The improved EMD algorithm is used to decompose the observed signals， and then the decomposed components together with the prior observed signals are regarded as new observed signals. Thus the underdetermined situation is changed into an overdetermined case. Finally， we use independent component analysis (ICA) algorithm to obtain the estimation of source signals. Simulation result shows that the proposed algorithm is effective. References | Related Articles | Metrics

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Quantitative Analysis on the Reproducibility of Four Kinds of Pulse Wave Sensors XU Li-sheng， SUN Nan-nan， YU Jing-yi， ZHANG Qian-qian 2018, 39 (8):  1114-1117.  DOI: 10.12068/j.issn.1005-3026.2018.08.010 Abstract ( 668 )   HTML   PDF (375KB) ( 634 )   Twenty healthy college students were selected as subjects. Four kinds of pulse wave sensors (adjustable， pencil probe， wrist-band， and photoelectric)were used to collect radial pulse waves. The influence factors， stability and reproducibility of the four sensors were studied. The results show that photoelectric sensor is susceptible to contact pressure， ambient light and measuring site， and it has medium reproducibility and poor stability; wrist-band pulse sensor is susceptible to measuring site， and its stability and reproducibility are medium; pencil probe sensor is susceptible to measuring site， and its stability and reproducibility are good; adjustable sensor is susceptible to pressure and measuring site， and it has good reproducibility and medium stability. Four kinds of pulse wave sensors have their own performance indexes and application scopes. The pencil probe sensor has less influence factors and better performance indexes. References | Related Articles | Metrics

Materials & Metallurgy

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Temperature Field in Annealing Process of Dual-Phase Steel TRB KE Di-wen， LIU Xiang-hua， ZHI Ying 2018, 39 (8):  1118-1122.  DOI: 10.12068/j.issn.1005-3026.2018.08.011 Abstract ( 613 )   HTML   PDF (589KB) ( 570 )   To gain cold rolled dual phase steel TRB (tailor rolled blank) with controllable performance， the annealing temperature variation during annealing is necessary to know. The temperature distribution of dual-phase steel TRB at different thickness in the annealing process was simulated by the finite element software ABAQUS. The results showed that when the different areas in TRB is in same cooling rate， the bigger the cooling rate is， the less gap between the ratio of the convection heat transfer coefficient， which changes from 2.12 to 2.03， and the ratio of thickness is. The convection heat transfer coefficient is directly proportional to cooling rate. When cooling intensity is same in different areas in TRB， the temperature difference between thick and thin area increases from 124℃ to 141℃ with increased cooling rate. If the slope of TRB increases， the length of temperature affected zone increases. References | Related Articles | Metrics

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Development and Strengthening Mechanism of 420MPa Grade Bridge Steel with High Toughness GAO Cai-ru， LIU Bao-xi， PAN Huan， GAO Xiu-hua 2018, 39 (8):  1123-1126.  DOI: 10.12068/j.issn.1005-3026.2018.08.012 Abstract ( 658 )   HTML   PDF (950KB) ( 770 )   The Q420 bridge steel with yield strength of 480~ 530MPa， tensile strength of 560~ 630MPa， elongation of 21 %~ 25% and impact strength of more than 200J at-20℃was developed by optimization of alloy composition and improvement of control rolling and control cooling process. The amount of various types of strengthening contribution was obtained through analyzing the amount of precipitation by transmission electron microscopy and the grain size of metallographic microstructure. Then the strengthening mechanism of Q420 bridge steel was studied. The results showed that the contribution of precipitation strengthening accounts for less than 10% of the total strength for Q420 bridge steel， and the contribution of solid solution strengthening and fine grain strengthening are 54% and 36%，respectively.It is confirmed that solid solution strengthening and fine grain strengthening are dominated in 420MPa grade steel. References | Related Articles | Metrics

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Effect of Substrate Steel Crystallographic Features on Coating Phase Structure and Powdering Resistance DENG Yong-gang， PAN En-bao， LI Yun-long， DI Hong-shuang 2018, 39 (8):  1127-1131.  DOI: 10.12068/j.issn.1005-3026.2018.08.013 Abstract ( 523 )   HTML   PDF (8082KB) ( 611 )   In order to improve the powdering resistance of galvannealed coating， the effects of substrate steel crystallographic features on the galvannealed (GA) coating phase structure and powdering behavior were studied. The results show that γ texture can improve the formability of substrate and retrain the crack propagation of coating. The presence of (111)-(113)-(313)//RP at the top of the substrate promotes the formation of δ phase. However， ζ phase with high growth rate are formed on (001)-(101)//RP of substrate steel. ζ phase is transformed into δ phase and finally transformed into Γ phase during the galvannealed processes and led to different phase structures， thus affecting powdering properties and adhesive between coating and substrate. Additionally， both the ratio of volume fraction of 113〈110〉to that of 111〈110〉， and the fraction of high (low) energy boundaries play a vital role in the formation and growth of Fe-Zn intermetallic phase. References | Related Articles | Metrics

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Microstructures and Mechanical Properties of Laser Rapid Prototyping Deposited TC4 Alloy LIU Jing， LIU Yi-ting 2018, 39 (8):  1132-1136.  DOI: 10.12068/j.issn.1005-3026.2018.08.014 Abstract ( 637 )   HTML   PDF (784KB) ( 668 )   Microstructures and mechanical properties of laser rapid prototyping deposited TC4 alloy in the parallel and vertical directions were studied by metallographic microscope， scanning electron microscopy and electronic tensile testing machine. The results showed that the β grains growing in the deposited direction are coarse and columnar， which shows a bright and dark strip structure and is typical Widmanstatten structure. The strength vertical to deposition direction is higher than that parallel with deposition direction， but the plasticity is low. The fracture of the alloy is dimple fracture， and the size of the dimples on the fracture vertical to deposition direction is smaller than that parallel with deposition direction. References | Related Articles | Metrics

Mechanical Engineering

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Simulating and Experimental Investigations on Aerodynamic Noise of High-Speed Train Head JIANG Shi-jie， YANG Song， WU Dan， WEN Bang-chun 2018, 39 (8):  1137-1142.  DOI: 10.12068/j.issn.1005-3026.2018.08.015 Abstract ( 675 )   HTML   PDF (1265KB) ( 714 )   The full-size high-speed train head and flow field around were modeled to simulate the turbulent air flow and aerodynamic noise. The external steady flow field was computed using the Realizable k-ε turbulence model. Based on the steady flow field， aerodynamic noise sources on the train head surface and the external transient flow field were calculated by broadband acoustics source model and large eddy simulation (LES)， respectively. The fluctuating pressures on the train surface were obtained from the results of the transient model. Considering the transient flow field， the far-field aerodynamic noise of the train head was finally obtained based on Lighthill acoustics analogue theory. The simulated aerodynamic noise was compared with the on-line test result to validate the simulation， and they have a good agreement. References | Related Articles | Metrics

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A New Rotating Blade-Casing Rubbing Model Considering Flexibility of Casing LI Bing-qiang， MA Hui， HAO Yu-ming， XIE Fang-tao 2018, 39 (8):  1143-1148.  DOI: 10.12068/j.issn.1005-3026.2018.08.016 Abstract ( 622 )   HTML   PDF (618KB) ( 606 )   Aiming at rubbing fault between rotating blade and casing， and taking elastic blade and flexible casing as studying objects， a new rotating blade-casing rub impact model was deduced based on elastic compatibility condition. Then considering centrifugal stiffening， rotating softening and rubbing softening， the quasi-static bending displacement of blade was calculated based on relevant theory of material mechanics. The casing was simulated as an elastic ring with spring support， and the displacement was composed of rigid-body and local-flexible displacements. The displacement equation of the flexible ring was established according to the principle of energy conservation， and the structural stiffness followed by local flexible displacement of the casing was obtained by discrete processing. Because of more parameters considered， the model has a good generality. Compared with the experimental data and the literature， the model can meet the requirements of calculation with a higher accuracy. References | Related Articles | Metrics

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Numerical Modeling and Test of Braking Time on Magneto-rheological Brake SONG Wan-li， TAO Yan， HU Zhi-chao， WANG Na 2018, 39 (8):  1149-1153.  DOI: 10.12068/j.issn.1005-3026.2018.08.017 Abstract ( 689 )   HTML   PDF (681KB) ( 725 )   To study the relationship between the braking time and the working gap of the magneto-rheological brake (MRB)， the calculating formula of braking time on the MRB was deduced based on the Bingham theory model and the ANSYS magnetic field simulation. The braking time corresponding to different rotating angular velocities under different working gaps was calculated based on the formula and the measuring test of braking time and rotational angular velocity under different working gaps was carried out based on MRB with adjustable working gap. Comparing the theoretical value with the experimental one， the braking time is shown to increase linearly with the working gap， and the correctness of the theoretical calculation formulas was verified. The braking time under different currents was measured， and the nonlinear relationship between the braking time and current under the same working gap was proved. References | Related Articles | Metrics

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Chatter Feature Extraction Method in Variable Cutting Depth Flank Milling Based on VMD and FFT LIU Chang-fu， ZHU Li-da， QIU Jian， LI Ming 2018, 39 (8):  1153-1157.  DOI: 10.12068/j.issn.1005-3026.2018.08.018 Abstract ( 641 )   HTML   PDF (949KB) ( 769 )   A chatter frequency band extracting method combining the variational mode decomposition (VMD) and fast Fourier transform (FFT) was proposed for extracting the obscure chatter frequency band in milling process， making good basis of further extracting the chatter feature value. To obtain the frequency band including chatter frequency， the variable cutting depth flank milling experiment was carried out and the forces were measured in the experiment. A method of choosing the number of modes in the VMD by combining the FFT spectrum was proposed. The simulation signal and experiment signal were extracted by the above method. The results show that the method of combining the VMD and FFT can effectively extract the chatter frequency bands in milling， which offers a new method to extract the chatter feature. References | Related Articles | Metrics

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Adaptive Control of Piezoelectric Ceramic Actuator with Composite ADRC GAO Jin-hai， HAO Li-na， XIANG Chao-qun， QI Zi-xuan 2018, 39 (8):  1158-1162.  DOI: 10.12068/j.issn.1005-3026.2018.08.019 Abstract ( 753 )   HTML   PDF (937KB) ( 749 )   To eliminate the influence of the inherent hysteresis phenomenon of the piezoelectric ceramic actuator， a control scheme based on the combination of the active disturbance rejection control (ADRC) and the improved Preisach model is proposed. Taking the linearity of hysteresis loop of the model’s input and output as a criterion， the model is used to improve the positioning accuracy of the piezoelectric， thus improving the operating efficiency and success rate in bio manipulation. Through the experiments of different control schemes， the proportion of hysteresis loop is about 12.3% (no control)， 5.8% (improved inverse Preisach control)， 4.7% (composite PID)， 2.5% (ADRC)， 1.4% (composite ADRC). The experimental results comparisons prove that the control scheme proposed has good performance. References | Related Articles | Metrics

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Coal Seam Hardness Hierarchical Identification Method Based on BP Neural Network LIU Yong-gang， HOU Li-liang， QIN Da-tong， HU Ming-hui 2018, 39 (8):  1163-1168.  DOI: 10.12068/j.issn.1005-3026.2018.08.020 Abstract ( 650 )   HTML   PDF (644KB) ( 593 )   A BP neural network algorithm based hierarchical identification method， which divides the coal seam hardness into six levels， was proposed for identifying the coal seam hardness. The identification signals were taken from the stator currents of both the cutting motor and the traction motor of the mining machine， as well as the pressure signal of the height adjustment cylinder. The wavelet packet decomposition was used for extracting the characteristics of each signal， and these signals were taken as the input signals for training and testing the neural network. The experimental results show that the identification accuracy reaches 96.7% and 93.3% toward the simulation data and the real data， respectively， validating the effectiveness of the method. The method proposed provides the foundation for precisely identification of coal seam hardness. References | Related Articles | Metrics

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Evaluation and Selection for Knowledge Resources in Cloud Manufacturing Environment CHEN You-ling， HUANG Dian， ZHANG Yue-yuan， ZHAO Jin-peng 2018, 39 (8):  1169-1174.  DOI: 10.12068/j.issn.1005-3026.2018.08.021 Abstract ( 594 )   HTML   PDF (443KB) ( 530 )   In order to solve the problem of selecting knowledge resources in the cloud manufacturing environment， a selection model is presented based on the capacity of knowledge service from the perspective of knowledge resources suppliers’ service capacity. Through establishing the system for evaluating the capacity of knowledge service， the variable precision roughness set algorithm is utilized to calculate the weight of each evaluation index， and the sensitivity coefficient is used to revise users’ preference in actual cases. All the candidates’ capacities of knowledge service are obtained， based on which to guide the cloud platform to select the best supplier for users. Finally， examples are given to prove that the model can select the best supplier for users. References | Related Articles | Metrics

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Simulation on Turbulence Characteristics in Three-Dimensional Sphere Packed Bed LIU Hong-sheng， JIANG Lin-song， WU Dan， XIE Mao-zhao 2018, 39 (8):  1175-1180.  DOI: 10.12068/j.issn.1005-3026.2018.08.022 Abstract ( 743 )   HTML   PDF (1199KB) ( 821 )   Discrete element software LIGGGHTS is introduced to reproduce the forming process of sphere packed bed by gravity， and a 3D random geometric model similar to the actual accumulation structure is presented. Two ordered models， the in-line packed model and the staggered packed model， are also established to contrast with the random packed model. CFD software of Fluent 14.0 is employed to study the turbulence flows in the packed bed. The effectiveness of the random model is validated by analysis of the macroscopic pressure drop and the resistance coefficient， and the velocity field and the turbulence parameters of the three structures are predicted and discussed. Simulation results show that the macroscopic resistance coefficient and the macroscopic pressure drop of the random packed bed model are consistent with the classical formula of Ergun， with maximum relative error less than 6%. Compared with the orderly packed bed， the random packed model is characterized with more homogeneous velocity field， larger tail vortex size， stronger disturbance and extremely larger turbulence dissipation. References | Related Articles | Metrics

Resources & Civil Engineering

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Multi-method Based Optimization of Crown Pillar Thickness from Open Pit to Underground XU Shuai， AN Long， LI Yuan-hui， LU Dong 2018, 39 (8):  1181-1186.  DOI: 10.12068/j.issn.1005-3026.2018.08.023 Abstract ( 608 )   HTML   PDF (2481KB) ( 693 )   Taking a project from open pit to underground mining in the Guilaizhuang Gold Mine of Shandong Gold Group Co.， Ltd. as an example， multiple methods including theoretical calculation， scaled span approach and analogy under similar conditions are employed to analyse the rational scope of crown pillar thickness. The influence of underground mining on the crown pillar and slope stability is analysed with different thickness crowns using the software FLAC3D. The calculation results show that the 10m thick crown pillar can be viewed as a turning point: when the thickness is less than 10m， the roof deformation caused by underground mining is large， and the thinner the crown pillar， the larger the displacement increment; when the thickness is over 10m， the roof deformation from underground mining is relatively small and tends to remain stable. References | Related Articles | Metrics

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Influence of Cutoff Grade on Optimum Pit Limit and Total Profit WANG Qing， GU Xiao-wei， XU Xiao-chuan 2018, 39 (8):  1187-1191.  DOI: 10.12068/j.issn.1005-3026.2018.08.024 Abstract ( 619 )   HTML   PDF (560KB) ( 747 )   The calculation method of the profit-maximizing cutoff grade， i.e.， the break-even grade， is first discussed and an equation is given. The influence of cutoff grade on optimum pit limit and total profit is analyzed through a case study. The findings are as follows: for given economic parameters， the cutoff grade used both in pit limit design and in production can be selected in a relatively wide range. When the cutoff grades in both design and production change in these respective ranges， the total profit of the optimum pits is almost equal to that at the break-even grade. For different concentrate prices， these selection ranges only differ a little， though the volume and the total profit of the optimum pits differ a great deal. References | Related Articles | Metrics

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Effect of N，N-2 (3-chloride，2-hydroxypropyl) Dodecylamine on Flotation Desilicication of Magnesite Ore LIU Wen-bao， LIU Wen-gang， ZHANG Nai-xu， LI Zhen 2018, 39 (8):  1192-1196.  DOI: 10.12068/j.issn.1005-3026.2018.08.025 Abstract ( 832 )   HTML   PDF (444KB) ( 642 )   Flotation behavior of quartz， magnesite and dolomite in the presence of N，N-2 (3-chloride，2-hydroxypropyl)dodecylamine(NCDA) was investigated by flotation experiments. Properties and adsorption mechanism of NCDA were analyzed by zeta potential test， group electronegativity criteria and quantum chemistry calculation. Flotation results showed that， under the natural pH value of ore pulp， while the same dosages of collectors are added， NCDA has better ability to collect quartz than DDA， but the collecting ability of NCDA to magnesite and dolomite is obviously weaker than that of DDA. Results of zeta potential tests showed that NCDA adsorb on quartz surface by electrostatic adsorption and hydrogen-bond interaction. The calculation results of group electronegativity， hydrophile-lipophile balance and frontier molecular orbital energy indicated that NCDA has better collecting and foaming properties than DDA. Meanwhile， it is easier to interact with the quartz surface. References | Related Articles | Metrics

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Numerical Analysis on Stability of Slope Considering Rainfall Infiltration WANG Shu-hong， HE Jian， YANG Tian-jiao 2018, 39 (8):  1196-1200.  DOI: 10.12068/j.issn.1005-3026.2018.08.026 Abstract ( 829 )   HTML   PDF (1563KB) ( 1342 )   Finite element software ABAQUS was utilized to simulate the coupling effect of seepage field and stress field in slope under rainfall conditions. Regarding the saltation of the displacement at a characteristic nodal and the formation of continuously plastic deformation as instability criterion， The safety factor of slope was numerically computed by strength reduction method to assess the slope stability. By analyzing safety factor and the evolution of pore pressure， how the rainfall infiltration affects slope stability can be explained. And the result was verified by actual slope case including the layer of clay. It was found that the higher the rainfall intensity is， the faster transient saturated zone will form， and the layer of clay can accelerate this process， threatening the stability of slope. Therefore， the shallow landslides may occur. The maximum decline of the safety factor occurs during 24h rainfall. This research provides good reference to slope monitoring and slope anti-slide measures. References | Related Articles | Metrics

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A Preparation Technology and Construction Method of Implantable Ecological Slope Protection LI Rui， HUANG Yong-gang， HU Xiao-min 2018, 39 (8):  1201-1204.  DOI: 10.12068/j.issn.1005-3026.2018.08.027 Abstract ( 580 )   HTML   PDF (696KB) ( 550 )   The slope protection made of engineering materials or the traditional ecological slope protection will disturb river slopes to a certain extent， which will change the original habitat and endanger the river ecological system at different levels.Aiming at this problem， a new type of implantable ecological slope protection was developed. This kind of slope protection is mainly made of surplus sludge from municipal sewage treatment plants. CaO and MgCl2were used as the microbial inactivating agent and gelatinizing agent. The above materials were mixed with appropriate grass seeds and certain amounts of water to produce implantation mud(IM).Driven by pumps， the IM was injected into the soil under the earth surface from 10cm to 50cm through a rapidly rotating(1000r/min) injector. The grass seeds would sprout in the IM. About 20 days later， the grass would grow and the ecological slope protection would come into being. On the one hand， this method could take advantage of the surplus sludge’s water-retaining property and fertilizing effect; on the other hand， the special rotating injection technology was expected to have less disturbance to the surface soil. Therefore， this kind of ecological slope protection could not only keep slope stability but also conserve habitats perfectly， which would be beneficial for the sustainable and healthy development of the river ecosystem. References | Related Articles | Metrics

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Effects of C/N on the Denitrification Efficiency of SBR Enhanced by Aerobic Denitrifying Bacteria ZHAO Xin， LIU Fang， ZHAO Yan， HU Xiao-min 2018, 39 (8):  1205-1210.  DOI: 10.12068/j.issn.1005-3026.2018.08.028 Abstract ( 550 )   HTML   PDF (1043KB) ( 707 )   Two strains of Pseudomonas with efficient aerobic denitrification ability were used in the bio-augmentation process of sequencing batch reactor. In the 61 days’ operating process， the effects of C/N on the microbial community structures and denitrification efficiency were investigated. Although the denitrification efficiencies obviously decreased with the C/N decreasing， the performances of bio-augmentation groups were better than those of the negative control. Adding efficient aerobic denitrifiers into activated sludge enhanced the NO-3-N removal rate by about 14.1%， whereas the pure-cultured group was enhanced by 22.6%. Bio-augmentation with aerobic denitrifiers enhanced the proportion of denitrifiers， promoted them to be the dominant functional population， shortened the system’s start-up period， greatly enhanced the denitrification efficiency， and improved the stability of the microbial community structure and the system’s operation. This technique is more advantageous in the treatment of C/N>10∶1 wastewater containing nitrate. References | Related Articles | Metrics

力学

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A Modeling Approach of Elastoplastic Contact for Analyzing the Vibration and Energy Dissipation Characteristics of Particles LI Jian， GAO Wei， ZHANG Ya-shuang， LIU Yu-nuo 2018, 39 (8):  1211-1216.  DOI: 10.12068/j.issn.1005-3026.2018.08.029 Abstract ( 590 )   HTML   PDF (968KB) ( 661 )   A general contact modeling method of elastoplastic contact between particles is proposed to study the vibration and energy dissipation characteristics of the particle system. The basic form of constitutive equation concerning normal plasticity contact between particles is established and a dimensionless constitutive relation can be obtained based on the finite element method accordingly. A loading-unloading multipath model of elastoplastic contact between particles is presented. A theoretical formula of normal plastic energy dissipation is deduced. Based on the discrete element method， numerical simulations on the characteristics of vibration and energy dissipation for the particle system under harmonic excitation are carried out. The results show that the linear system exhibits the characteristics of nonlinear vibration caused by particles. Granular media appears to be a complicated nonlinear state of motion similar to the chaos near the resonance region. Although the way of energy dissipation on particle damping effect remains unchanged， normal plastic contact alters the dynamic contact behavior between particles and has great influence on the dynamic characteristics of the vibrating particle system. References | Related Articles | Metrics