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15 November 2015, Volume 36 Issue 11 Previous Issue    Next Issue
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Information & Control

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Economic Operation Optimization of Smart Microgrid Based on Scenario Methodology JIN Shao-zhen， MAO Zhi-zhong， LI Hong-ru 2015, 36 (11):  1521-1525.  DOI: 10.12068/j.issn.1005-3026.2015.11.001 Abstract ( 789 )   HTML   PDF (623KB) ( 769 )   According to the characteristics of economic dispatch problem for smart microgrid with uncertainties related to the forecasted errors for renewable energy sources (RESs)， a methodology based mixed 0-1 stochastic nonlinear programming was proposed. The roulette wheel mechanism (RWM) and Lattice Monte Carlo simulations (LMCS) were used to generate scenarios. By means of this strategy， the stochastic problem was converted to a number of deterministic problems with different probabilities. Meanwhile， branch and bound algorithm was employed to solve each of the deterministic problems. Consequently， the solutions obtained from the accepted scenarios were aggregated according to the probability to find the expected result of the investigated problem considering uncertainty. The validity of this optimization methodology was proved by the simulation results. References | Related Articles | Metrics

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Face Recognition Algorithm Based on MBC and POEM Feature ZHANG Xiang-de，ZHU He-gui， LI Qian-ying， TANG Qing-song 2015, 36 (11):  1526-1529.  DOI: 10.12068/j.issn.1005-3026.2015.11.002 Abstract ( 822 )   HTML   PDF (355KB) ( 660 )   Due to the representation difficulty of a face image by a single type feature used in face recognition， a MBC feature and POEM feature-based face recognition scheme was proposed. Firstly，MBC and POEM coding patterns were extracted from normalized face images. Secondly， feature vector of every block was generated by dividing the MBC and POEM coding patterns into blocks. Finally， the classification capacity of features was enhanced by using weighted piecewise LDA algorithm. Recognition and verification test were carried out using the proposed algorithm on Dup1，Dup2， Fb and Fc， respectively， which were the four subsets of FERET. The recognition rates were 93.77%， 90.60%， 99.58%， and 99.49%， respectively， and the verification rates(false accepted rate is 0.1%) were 95.70%， 92.31%， 99.75%， and 100% ， respectively. All these results indicated the effectiveness of the proposed algorithm. References | Related Articles | Metrics

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The Congestion Road Segment Prediction Based on GPS Trajectory Data LIN Shu-kuan， YU Ling-zi， QIAO Jian-zhong， ZHANG Bai-he 2015, 36 (11):  1530-1534.  DOI: 10.12068/j.issn.1005-3026.2015.11.003 Abstract ( 1010 )   HTML   PDF (333KB) ( 1128 )   Congestion road segments over real GPS trajectory data was predicted. The traditional methods were ostracized based on traffic flow prediction and congestion identification， and a novel method was proposed based on the congestion vector and the congestion transition matrix. The congestion vector and the congestion transition matrix were established by mining and training taxi GPS trajectory data， resulting in the implementation of the prediction of traffic congestion. In the course of prediction， time periodicity and spatial-temporal correlation of road segment congestion were both considered. The experiments on real data show the effectiveness of the congestion road segment prediction method proposed. References | Related Articles | Metrics

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An Improved Envelope Fitting Algorithm for the Empirical Mode Decomposition WU Xian-gui， WANG An-na， HUI Guo-tao 2015, 36 (11):  1535-1539.  DOI: 10.12068/j.issn.1005-3026.2015.11.004 Abstract ( 826 )   HTML   PDF (516KB) ( 750 )   Due to the envelope fitting problem exists in the process of empirical mode decomposition， an improved algorithm was proposed which could eliminate the undershoot phenomenon exactly. Firstly， in this improved algorithm， the cubic spline interpolation was used to determine the regions of undershoot which generated during the execution of envelope fitting. Secondly， the envelope intervals of undershoot regions were compensated by the monotone piecewise cubic polynomial interpolation. The original signal could be wrapped tightly by this modified envelope， which did not affect the characteristics of signal itself， and could keep the smoothness of previous envelope as well as possible. The simulation results showed that the undershoot phenomenon caused by cubic spline interpolation could be effectively eliminated and the envelope could be obtained better by this algorithm. In addition， the accuracy of empirical mode decomposition could be further improved. References | Related Articles | Metrics

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Sampling Based Uncertain Extreme Learning Machine ZHAO Xiang-guo， BI Xin， ZHANG Zhen， YU Xin 2015, 36 (11):  1539-1542.  DOI: 10.12068/j.issn.1005-3026.2015.11.005 Abstract ( 712 )   HTML   PDF (307KB) ( 670 )   Large amounts of data in real-world applications have inherent uncertainty. Traditional learning algorithms cannot be applied directly onto uncertain datasets. Aiming at classification problems over uncertain data， a sampling based uncertain ELM(extreme learning machine) was proposed. Instances were first sampled out of uncertain objects， and then learnt with uncertain ELM. The uncertain objects would be assigned to their classes respectively according to the probabilities aggregation method. The classification was realized by the proposed algorithm in this paper over uncertain data avoiding the enumeration of instances. The experimental results indicated the efficiency and effectiveness of our algorithm. References | Related Articles | Metrics

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A Graph Compression Based Overlapping Communities Detection Algorithm ZHAO Yu-hai， YIN Ying， WANG Xue 2015, 36 (11):  1543-1547.  DOI: 10.12068/j.issn.1005-3026.2015.11.006 Abstract ( 562 )   HTML   PDF (343KB) ( 740 )   To improve the capacity of single machine to handle complex network，overlapping communities detection algorithm was proposed. First， a graph compression based social network model， namely agglomerative graph， was introduced， which was a lossless compression to the original network. Then， inspired by the idea of iteration based on seeds， the selected seeds were expanded to the communities by optimizing the proposed community fitness function iteratively. Finally， the communities of high similarity with each other were merged to get the final results. Since the scale of the network to be dealt is significantly reduced， and some redundant computations are avoided， the proposed algorithm is of high efficiency. References | Related Articles | Metrics

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A Session Negotiation Mechanism in IMS Supporting Relay-based Media Multipath Transport ZHANG Wei， LEI Wei-min， LI Guang-ye， GUAN Yun-chong 2015, 36 (11):  1548-1553.  DOI: 10.12068/j.issn.1005-3026.2015.11.007 Abstract ( 579 )   HTML   PDF (692KB) ( 640 )   Due to IMS(IP multimedia subsystem) does not support media relay-based multipath transmission mode at present， a session negotiation mechanism in IMS supporting media relay-based multipath transport was presented. Multipath transmission function was introduced to IMS system in a form of service. The multipath transport framework based on application-layer relay was combined with IMS system seamlessly. The network side of IMS was enabled to manage media multipath transmission process. The proposed mechanism not only maximize the reuse of existing IMS network infrastructure to protect the early capital investment and improve the scheme’s practicability， but also enable the network side of IMS to have the ability to provide users with differentiated media transmission quality. References | Related Articles | Metrics

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A Digital Image Matting Algorithm Based on the Optimization Strategy of Latent Radius ZHAO Hai， LEI Kai-ru， ZHU Hong-bo， PIAO Chun-he 2015, 36 (11):  1553-1557.  DOI: 10.12068/j.issn.1005-3026.2015.11.008 Abstract ( 493 )   HTML   PDF (580KB) ( 642 )   Due to parameters is needed to be set depending on the issue of human goal-oriented to filter matting algorithms， a classifier was proposed based on component detection called LSVM (latent support vector machine). The parameters of guided radius could be automatically set so as to optimize algorithm. Firstly， for determining the radius， a potential idea of LSVM was applied which using the known database templates to train the input samples of the target image， then the sample set of the guided image and the binary image were divided into blocks with different radius which could automatically generate the reasonable parameters and optimize algorithm. At last， guided filter was used to advance matting and the intelligent and flexible of the matting algorithm was achiered. References | Related Articles | Metrics

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Gravity Training Method ZHANG Peng， LI Ping， LI Qing-rui 2015, 36 (11):  1558-1561.  DOI: 10.12068/j.issn.1005-3026.2015.11.009 Abstract ( 761 )   HTML   PDF (526KB) ( 617 )   A new training method was proposed to solve the problem that some gradients of the objects are not easy to calculate. This method was based on the principle of gravity optimizes parameters. Random initial parameter based on step was set as coordinate form which in the midpoint of the multidimensional space. The error between the actual output and the target output was set as radius. This method had advantages which could not need to calculate the gradient and could randomly select initial value. This method was successfully used in the PID controller， LQR controller and neural network. References | Related Articles | Metrics

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A Method for Lightweight Verification on Data Integrity in Mobile Cloud Computing Environment SHEN Zhi-dong， LIN Chen， TONG Qiang 2015, 36 (11):  1562-1566.  DOI: 10.12068/j.issn.1005-3026.2015.11.010 Abstract ( 609 )   HTML   PDF (494KB) ( 719 )   The data integrity verification in mobile cloud computing environment was analyzed. A method for lightweight verification on data integrity was proposed， which was based on BLS short signature scheme and Merkle Hash tree data structure. Considering the resource constraints and “harsh” environment of mobile devices， the method is suitable for mobile computing environment and has many good features of proposed schemes. Through the method the verification process could be accomplished with high accuracy， light computing and low data transmission. In this method， outsourcing verification was supported， data integrity could be verified without using directly source file blocks， process of verification could be stateless， and dynamic data operation could be archived in cloud. It is suitable for the service on data in mobile cloud computing environment. References | Related Articles | Metrics

Materials & Metallurgy

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Mechanism of Microstructure Evolution in Low Carbon Steels by Flash Processing LU Ri-huan， LIU Xiang-hua， YAN Shu， LIU Li-zhong 2015, 36 (11):  1567-1571.  DOI: 10.12068/j.issn.1005-3026.2015.11.011 Abstract ( 711 )   HTML   PDF (960KB) ( 819 )   The mechanism of microstructure evolution of low carbon steels Q195 and CR340 during flash processing was studied by utilizing hot simulation device. The results indicated that complex microstructure consisting of martensite， bainite， ferrite and undissolved cementite was observed in the early stage of flash processing. The average concentration of carbon increases owing to the gradual dissolution of undissolved cementite， leading to the decrease of carbon concentration in austenite grain. Finally， the relative amount of martensite increases， and the microstructure is wholly comprised of lath martensite. Comparing with the traditional quenching process， flash processing can significantly refine grain size of experimental steels. Simultaneously， the role of grain refinement will become more obvious by increasing heating rate. References | Related Articles | Metrics

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Effects of Forging Pass on the Structure of 5182 Aluminum Alloy During Multi-direction Forging Process ZHU Qing-feng， WANG Jia， ZUO Yu-bo， CUI Jian-zhong 2015, 36 (11):  1572-1576.  DOI: 10.12068/j.issn.1005-3026.2015.11.012 Abstract ( 630 )   HTML   PDF (630KB) ( 728 )   Macro- and micro-structure evolution of 5182 aluminum alloy was studied in multi-directional forging (MDF) with the final forging temperatures of 340 ℃. The results showed that the fine grain zone in the center of sample expands gradually with the increment of the forging passes from 3 to 12. But increasing the forging pass to 12 can not eliminate the structure difference between the center and peripheral area. The structure of area near the forging harmers is constantly destroyed (but no distinct recrystallization occurs in the structure) with the forging pass increases from 3 to 12. When the forging pass is 3， partial recrystallization occurs on the center area of the sample. When the forging pass reaches 6， a fully recrystallization occurs in the center area of the sample， and the finest recrystallization grains are observed. With the forging pass further increases to 9 and 12， the recrystallization grains are a little coarser than that forged by 6 passes. However， the grains in the center area of the samples forged by 9 and 12 passes show the almost same size. So there is a grain refinement limitation in the center of sample with the increment of the forging passes. References | Related Articles | Metrics

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Hot Rolling Process and Microstructures of X70 Pipeline Steel Under Ultra-Fast Cooling KANG Jian， ZHAO Jin-hua， WANG Xue-qiang， DI Hong-shuang 2015, 36 (11):  1576-1580.  DOI: 10.12068/j.issn.1005-3026.2015.11.013 Abstract ( 575 )   HTML   PDF (657KB) ( 636 )   The microstructures and mechanical properties of 14.2 mm X70 pipeline steel， which undergoing ultra-fast cooling+laminar cooling and single laminar cooling after finish rolling， were compared and analyzed. The strengthening and toughing mechanisms were discussed for ultra-fast cooling methods. The results indicate that the mechanical properties of the experimental steel at both cooling methods can meet the API SPEC 5L X70 criterions. The microstructures consist of bainitic ferrite， acicular ferrite and M-A island， and the mixture microstructures of acicular ferrite and M-A island can be refined at the condition of ultra-fast cooling+ laminar cooling. The main strengthening mechanisms are grain refinement strengthening and nano-scale precipitation strengthening. The ideal cooling method after rolling for 14.2mm X70 pipeline steel is listed as: finish rolling at temperature of 820~840℃+ ultra-fast cooling to temperature of 450~500℃+laminar cooling to 350~400℃+ coiling. References | Related Articles | Metrics

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Cell-Based Smoothed Finite Element Method for Piezoelectric Materials with Cracks ZHOU Li-ming， MENG Guang-wei， WANG Hui， LI Feng 2015, 36 (11):  1581-1585.  DOI: 10.12068/j.issn.1005-3026.2015.11.014 Abstract ( 555 )   HTML   PDF (688KB) ( 577 )   Cracks in the piezoelectric material restricts wider application of the piezoelectric material and further improvement in the performance of related devices. To improve the accuracy and efficiency of solving the fracture parameters of piezoelectric materials， the complex potential function method and Cell-based smoothed finite element method(FEM) are introduced to fracture mechanics of piezoelectric materials， and Cell-based smoothed FEM for the piezoelectric materials with cracks was established. Normalized intensity factors of the center cracked piezoelectric with different materials， crack length， meshes and smoothing subcells were discussed and compared with FEM. Numerical example results showed that the Cell-based smoothed FEM， improving the FEM stiffness with high precision and high efficiency， is efficient numerical methods. References | Related Articles | Metrics

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Temperature Revolution During Feeding Process in ESR of 1Mn18Cr18N ZHU Hong-chun， JIANG Zhou-hua， LI Hua-bing， LI Ke-bin 2015, 36 (11):  1586-1590.  DOI: 10.12068/j.issn.1005-3026.2015.11.015 Abstract ( 778 )   HTML   PDF (679KB) ( 706 )   The temperature field at quasi steady state of electro slag remelting (ESR) was taken as initial condition in the simulation of temperature distribution during ESR in virtue of ANSYS and CFX. Terminal positions of hot spots in the ingot under three feeding conditions (i.e. no feeding， linear current-drop and stair-step current-drop during feeding) were investigated. The results showed that the largest distance of mushy zone around the hot spot were 162mm， 130mm and 70mm away from slag-metal interface， when no feeding， linear current-drop and rapid stair-step current-drop were carried out during ESR feeding process， respectively. The hot spot remained changeless under slow stair-step current-drop. Thus， stair-step current-drop is beneficial for feeding process during ESR of 1Mn18Cr18N. References | Related Articles | Metrics

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Deoxidation Thermodynamics and Slag Designing in ESR Process for Alvminum-Titanium Alloy HOU Dong， DONG Yan-wu， JIANG Zhou-hua， ZHOU Wei-ji 2015, 36 (11):  1591-1595.  DOI: 10.12068/j.issn.1005-3026.2015.11.016 Abstract ( 687 )   HTML   PDF (480KB) ( 739 )   A thermodynamics model for deoxidation in 1Cr21Ni5Ti system with Al as a deoxidizer and a slag designed for this system was developed based on ion and molecule coexistence theory (IMCT)， thermodynamics equilibrium and mass conservation. The equilibrium mass fractions of Si， Al， Mn in steel and the TiO2 content in slag designed for controlling the ［Ti］ were obtained depending on the increasing Al content. The results showed that the mass fractions of Si， Al， Mn and Al2O3 increase with increasing Al content， while the mass fractions of SiO2， FeO， MnO and TiO2 content tend to decrease. When Al content increases to 0.2%， the Al mass fraction in steel may increase with little unstable oxide in slag and the deoxidizer Al dissolving into steel. Considering the limitation of Si， Al， Mn mass fraction and little wave of Ti， the amount of Al added in one ton steel should not exceed 0.15% and the TiO2 content designed for controlling Ti is 4%. References | Related Articles | Metrics

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Desilication of Boron Mud Using Molten Sodium Hydroxide Media NING Zhi-qiang， LI Xiao-xia， ZHAI Yu-chun， JIA Chao-hang 2015, 36 (11):  1596-1600.  DOI: 10.12068/j.issn.1005-3026.2015.11.017 Abstract ( 509 )   HTML   PDF (755KB) ( 704 )   To accomplish the comprehensive utilization of boron mud， the desilication of boron mud was studied using molten sodium hydroxide media. The effect on silicon dioxide extraction ratio caused by the factors， such as reaction time， reaction temperature and mass ratio of sodium hydroxide to boron mud， was analyzed. The optimum reaction condition of desilication was obtained through the orthogonal tests. The results showed that the extraction ratio of silicon dioxide reaches 91.9% and MgO content reaches 92.04% in the solid residuals under the optimum reaction conditions of desilication. The reaction time is 20min， the reaction temperature is 550℃ and the mass ratio of sodium hydroxide to boron mud is 1.75∶1. The solid residuals were characterized by XRD and SEM. References | Related Articles | Metrics

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Solidification Behaviour and Viscosity Behaviour of Blast Furnace Slag Modified by Tailings LI Jie ， LIU Wei-xing， ZHANG Yu-zhu， ZHAO Kai 2015, 36 (11):  1601-1604.  DOI: 10.12068/j.issn.1005-3026.2015.11.018 Abstract ( 600 )   HTML   PDF (636KB) ( 742 )   Tailings of different mass fractions were added into the blast furnace slag (BF slag) as the modifier， and the solidification behaviour and viscosity behaviour of the modified molten slag were studied. Mineral composition and microstructure of the modified molten slag were analyzed by X-ray diffraction (XRD) and polarizing microscope. The viscosity curves between 1200℃ and 1475℃ were studied by synthetic test instrument for the physical characteristics. The results indicated that when the acidity coefficient (Mk) of the molten slag reaches 1.2~1.8 after adding tailings， the solidification structure of the molten slag has mainly an amorphous/vitreous character， and the microstructure is a compact and uniform structure except for Mk=1.8. In addition， the suitable temperature range for melting fabrication is significantly increased. The appropriate mass fraction of tailings is 16.98%~34.18%. References | Related Articles | Metrics

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Effects of Reaction Conditions on Phosphorus Removal by Steel Slag YANG He， WANG Zhen 2015, 36 (11):  1605-1608.  DOI: 10.12068/j.issn.1005-3026.2015.11.019 Abstract ( 570 )   HTML   PDF (576KB) ( 646 )   Steel slag has already been used to deal with all kinds of wastewater due to its larger specific surface area， porosity and density， its easy solid-liquid separation and not easy to form secondary pollution. In order to ensure the influence of reaction conditions on the steel slag phosphorus removal effect， many factors such as phosphorus in sewage initial concentration， dosage of steel slag， steel slag particle size， temperature， pH value were investigated. The results showed that reaction equilibrium is faster when the initial concentration of phosphorus is higher， and the effects on total phosphorus removal is greater. With the increase of dosage of steel slag， the decrease of steel slag particle size， the quantity of phosphorus removal has a significant increase. Steel slag for phosphorus removal is appropriate in the acidic conditions， the rate of removal is highest when pH=4. Steel slag has a little effect on treatment effect under the condition of temperature of 20 ~ 35℃. References | Related Articles | Metrics

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Effect of w(MgO)/w(Al2O3) Ratio on Desulfurization Capacity of BF Slag YUAN Xiang， ZHANG Jian-liang， MAO Rui， LIU Zheng-jian 2015, 36 (11):  1609-1613.  DOI: 10.12068/j.issn.1005-3026.2015.11.020 Abstract ( 1182 )   HTML   PDF (685KB) ( 747 )   The desulfurization process when liquid iron dropped across slag using a double-deck crucible was simulated to study the effect of MgO and Al2O3 on the desulfurization capacity of slag and clarify the relationship between w(MgO)/w(Al2O3) ratio and sulfur content in slag system. The results confirmed that desulfurization capacity increases gradually when the content of MgO increases from 6% to 12%， while further increases MgO content from 12% to 14% leading to the decrease of desulfurization capacity. The desulfurization capacity decreases slightly when Al2O3 content increases from 9% to 15%， while further increase of Al2O3 from 15% to 17% decreases the desulfurization capacity greatly. This study proposes that the desulfurization capacity of slag can be improved obviously by increasing w(MgO)/w(Al2O3) ratio when the content of MgO is less than 12% and content of Al2O3 is less than 15%. References | Related Articles | Metrics

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Behavior of Non-metallic Inclusions of IF Steel During Production Process QIN Yi-ming， WANG Xin-hua ， HUANG Fu-xiang ， JI Chen-xi 2015, 36 (11):  1614-1618.  DOI: 10.12068/j.issn.1005-3026.2015.11.021 Abstract ( 732 )   HTML   PDF (777KB) ( 900 )   The transition of non-metallic inclusions of IF steel produced by SGJT during RH refining and tundish was investigated. Molten steel samples were taken from 2 industrial heats systematically， and the compositions， size distribution and number of the inclusions were analyzed using Aspex scanning electron microscopy. The results showed that Ti alloying and reoxidation of molten steel results in the formation of Al2O3-Ti○xO inclusions， then these inclusions are transformed into Al2O3 inclusions during RH refining， which is in agreement with thermodynamic calculation. In addition， Al2O3 inclusions could be the nucleus of Al2O3-Ti○xO that wraps up them， and steel droplets outside enters into the interior of the inclusions in the transformation from Al2O3-Ti○xO to Al2O3， so steel droplets exists in the interior of Al2O3 inclusions. References | Related Articles | Metrics

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Optimization of Production Schedule Based on Ladle Running Stability in Steel Plant FENG Kai， HE Dong-feng， XU An-jun， WANG Hong-bing 2015, 36 (11):  1619-1623.  DOI: 10.12068/j.issn.1005-3026.2015.11.022 Abstract ( 614 )   HTML   PDF (449KB) ( 675 )   For the problem of the lack of guiding principle of production schedule in the case of non-full production in steelmaking plant， the optimization method of production schedule based on ladle running stability was proposed. First， the computational method of the number of online operation ladle was proposed by analyzing ladle turnaround process. Second， the impact of production schedule on ladle running was analyzed for the production schedule of single casting machine and two casting machine， and the computational model was proposed. Finally， the method was used to optimize actual production schedule of a steelmaking plant. The results showed that using genetic algorithm based on ladle running stability， the fluctuation of the number of ladle is reduced， the fluctuation of ladle thermal state is reduced， baking gas is saved， the temperature of BOF endpoint is reduced and the level of control the temperature of molten steel is improved. References | Related Articles | Metrics

Resources & Civil Engineering

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Analysis of Acoustic Emission Source Mechanisms for Tensile and Shear Cracks of Rock Fractures LIU Jian-po， LIU Zhao-sheng， WANG Shao-quan， LI Yuan-hui 2015, 36 (11):  1624-1628.  DOI: 10.12068/j.issn.1005-3026.2015.11.023 Abstract ( 666 )   HTML   PDF (572KB) ( 610 )   Acoustic emission (AE) technique was employed to measure the AE signals of granite for three-point bending tests and shear tests. The spatial-temporal distributions of various fractures micro-cracks were studied based on the simplex locating algorithm and moment tensor theory. The results showed that the micro-cracks generated from the three-point bending tests are mainly of tensile type， accounting for more than 50% of the total events. For the shear tests， the micro-cracks of shear type are prominent whose proportion is more than 60% with rock failure. Moreover， the results of the distribution of AE locations and moment tensors are in agreement with the macroscopic fractures at the end of the experiments， which can be used to describe the distribution and migration of tensile and shear stress when rocks are under loading. The results indicated that the moment tensor theory is a very useful method for studying AE source mechanisms and spatial-temporal vibrations of micro-cracks. References | Related Articles | Metrics

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Analysis of the Stability of Three-Hinged Arch Axis Curve Structure of Tilted Roofs ZHAI Hui-chao，REN Feng-yu，NAN Shi-qing 2015, 36 (11):  1629-1633.  DOI: 10.12068/j.issn.1005-3026.2015.11.024 Abstract ( 598 )   HTML   PDF (443KB) ( 524 )   A plastic hinge area was formed before the empty area in the roof corner lost its stability and the three-hinged arch bearing mechanism was formed due to stress redistribution. Based on this characteristic， the roof was approximately regarded as three-hinged arch axis curve structure with a half span， the mechanical model including span (L)， arch loss (f) and roof rock load (q(x)) was established to solve the caving line equation (y(x)) and arch axis equation (N(x))， the roof stability and the caving line form were analyzed， and the critical span and the critical exposure area were calculated. Taking Paishanlou Gold Mine for example， the conclusion of sub stable goaf was drawn with the critical span being 70m in transverse， 140m in the vertical dimension and the critical exposure area 7 693m2 by using the mechanical model. Therefore， the pillar mining is prohibited and the rapidly filling area is proposed so as to guarantee underground safety. References | Related Articles | Metrics

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Uniaxial Compression Test and Numerical Simulation of Stratified Biotite Granulite WANG Pei-tao ， YANG Tian-hong， YU Qing-lei， SHI Wen-hao 2015, 36 (11):  1633-1637.  DOI: 10.12068/j.issn.1005-3026.2015.11.025 Abstract ( 705 )   HTML   PDF (1068KB) ( 587 )   The transversely isotropic rock samples with different dip angles were studied under uniaxial compression using the bonded particle model (BPM) of PFC2D. The strength and failure patterns were explored and compared with the experimental results. The results showed that the mechanical properties are affected significantly when the ratio of joint contact bond strength (both shear and normal) to rock contact bond strength is below 15%. The failure pattern is similar to the experimental result when the ratio falls into the range of approxiamtely 2%~4%. The uniaxial compressive strength decreases firstly at a certain value with the increase of joint angles and increases subsequently with a U-shape. The results can provide a reference for jointed rock mass with PFC2D code. References | Related Articles | Metrics

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Numerical Simulation on the Anisotropy Seepage Characteristic of Water-Sealed Underground Oil Storage Caverns LIU Jie， ZHAO Xing-dong， WEN Xin-liang 2015, 36 (11):  1638-1642.  DOI: 10.12068/j.issn.1005-3026.2015.11.026 Abstract ( 622 )   HTML   PDF (814KB) ( 503 )   Taking a water-sealed underground oil storage cavern as the engineering background， the numerical simulation software of FLAC3D was adopted to analyze the distribution law of underground water seepage fields at the construction stage and operation stage. The difference of water pressure distribution in the fractured rockmass with and without seepage anisotropy was then compared. Finally， the seepage discharge of its surrounding rockmass was calculated. The results showed that the artificial water curtain system is of great importance to maintain the water sealing of caverns. Assuming the seepage of fractured rockmass， it is safer to evaluate the stability of rock pillars between caverns. The numerical simulation results of seepage discharge at the construction stage and operation stage are 1130m3/d and 775m3/d respectively. References | Related Articles | Metrics

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Research on Soil Dispersion of Qian’an Soil Forest ZHANG Xu-dong， WANG Qing， LI Peng-fei， WANG Rui-ying 2015, 36 (11):  1643-1647.  DOI: 10.12068/j.issn.1005-3026.2015.11.027 Abstract ( 710 )   HTML   PDF (517KB) ( 516 )   To study the properties of soil samples collected from Qian’an soil forest， two sampling points were chosen for vertical sampling and the dispersion identification was made. Based on the study of particle-size analysis and physicochemical analysis， the dispersion of the soil was determined by different identification methods， including pinhole test， crumb test and double-hydrometer test. The results showed that within the depth range from 0 to 1m， the silt particles account for a large proportion of the soil samples. The total soluble salt accounts for approximately 0.3% or above. The two sampling points display different change rules of the soluble salt. It is obvious that the shallow soils of these two sampling points are highly dispersive. At the first sampling point， the dispersion degree decreases with the increase of the depth， while it is not obvious at the second sampling point. References | Related Articles | Metrics

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Integrated Risk Assessment of Biomass Gasified Fire and Explosion Accidents YAN Fang， XU Kai-li， YAO Xi-wen， WANG Ben 2015, 36 (11):  1648-1652.  DOI: 10.12068/j.issn.1005-3026.2015.11.028 Abstract ( 734 )   HTML   PDF (1158KB) ( 558 )   In order to reduce the occurrence of fire and explosion accidents ， a risk assessment approach integrating Bayesian network and bow-tie analysis was proposed. Firstly， the fault tree is established and transformed into Bayesian network. Then the weak points which might lead to accidents can be pinpointed by calculating the importance of each basic event. The bow-tie analysis is given on the weak points to work out the precautions and control measures， and the reduction of accident frequency is calculated after taking control measures for the weak points. The reasons for such accidents can be found accurately by this approach， which helps to take appropriate precautions and control measures so as to effectively reduce the occurrence of biomass gasified fire and explosion accidents. References | Related Articles | Metrics

Mechanical Engineering

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Crack Propagation Simulation Caused by Collision Based on LS-DYNA Software MA Hui， ZENG Jin， WU Zhi-yuan， QIN Zhao-ye 2015, 36 (11):  1653-1657.  DOI: 10.12068/j.issn.1005-3026.2015.11.029 Abstract ( 1292 )   HTML   PDF (992KB) ( 949 )   The crack propagation path was simulated based on the piecewise linear plastic material model， which was caused by the collision between moving object and caging device using LS-DYNA software. Furthermore， four cases related to crack angles， crack depths， failure strains， and impact velocities were presented to analyze the crack growth laws. The results show that impact velocities and crack angles both have a great influence on crack propagation path， while crack depths or failure strains impacts relatively less. References | Related Articles | Metrics

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Normal Error of Tooth Surface Measurement and Analysis of Orthogonal Fluctuating Gear Ratio Face Gear LIN Chao， CAO Xi-jun， WANG Yao， XU Ping 2015, 36 (11):  1658-1662.  DOI: 10.12068/j.issn.1005-3026.2015.11.030 Abstract ( 537 )   HTML   PDF (785KB) ( 713 )   Aimed at orthogonal variable transmission ratio face gear machined by the 3-axis CNC， a solution of coordinate based on CNC gear measuring center was proposed to detect the normal error of tooth surface. A gridding of tooth surface was made and the theoretical coordinates and normal vectors of the grid nodes were calculated. The comparison with the result of the transmission test and the theoretical data obtained the deviations. At the same time， the fundamental change regularities of bias was analyzed. Finally， the results show that the approach presented is proved to be feasible. References | Related Articles | Metrics

Management Science

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Method for Determining the Proportion Between Long and Short Term Procurement for Raw Material Based on Similar Case Analysis DAI Xiang-quan， FAN Zhi-ping， WANG Yu-cai， LI Yong-hai 2015, 36 (11):  1663-1667.  DOI: 10.12068/j.issn.1005-3026.2015.11.031 Abstract ( 619 )   HTML   PDF (242KB) ( 638 )   A method was proposed to determine the proportion between long-term and short-term procurement for raw material based on similar case analysis. Firstly， the current problems of determining the proportion between long-term and short-term procurement are regarded as the target case， and some collected problems of proportion determination and the adopted procurement proportion programs in history are taken as the historical cases. Then， the similar historical cases are extracted by calculating the similarities between the target case and the historical cases. Furthermore， the utility of implementation effects for the procurement proportion program with regard to each similar historical case is calculated， and the better similar historical cases are screened by setting the utility threshold. On this basis， the current proportion program can be determined according to the screened similar historical cases. Finally， an empirical analysis is given to illustrate the feasibility and validity of the proposed method. References | Related Articles | Metrics

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Two-Sided Matching Model Between Domestic Service Staffs and Employers KONG De-cai， JIANG Yan-ping， JI Nan 2015, 36 (11):  1668-1672.  DOI: 10.12068/j.issn.1005-3026.2015.11.032 Abstract ( 789 )   HTML   PDF (238KB) ( 957 )   In order to achieve the optimal two-sided matching according to the supply and demand information of domestic service staff and employers， and to improve the efficiency of matching and reduce the cost of matching， the two-sided matching between domestic service staff and employers was studied. Firstly， the two-sided matching issue between domestic service staff and employers is described. Secondly， the satisfaction degree of domestic service staff and employers is calculated based on the supply and demand information provided by domestic service staff and employers， respectively. Furthermore， a multi-objective optimization model maximizing the staff and employers satisfaction degrees is constructed. A solution model is constructed to determine the corresponding optimal matching alternatives. Finally， a numerical example is given to illustrate the feasibility and effectiveness of the proposed method. References | Related Articles | Metrics