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    Information & Control
    Recursive Canonical Variate Analysis for Fault Detection of Time-Varying Processes
    SHANG Liang-liang, LIU Jian-chang, TAN Shu-bin, WANG Guo-zhu
    2016, 37 (12):  1673-1677.  DOI: 10.12068/j.issn.1005-3026.2016.12.001
    Abstract ( 716 )   HTML   PDF (481KB) ( 943 )  
    Because CVA (canonical variate analysis) is unable to adapt the characteristics of time-varying processes, by which the normal changes of the process is easily identified as faults, it is very necessary to propose a monitoring approach for time-varying processes. The exponential weighted moving average approach was adopted to update the covariance of the past observation vectors. The most critical problem faced by recursive CVA algorithm is the high computation cost. To reduce the computation cost, the first order perturbation theory was introduced to update recursively the singular value decomposition (SVD) of the Hankel matrix. The computation cost of recursive SVD based on the first order perturbation theory is significantly less compared to the SVD. Recursive canonical variate analysis based on the first order perturbation (RCVA-FOP) was applied in the Tennessee Eastman chemical process. Simulation results indicate that the proposed method not only can effectively adapt to the normal change of time-varying processes, but also can detect two types of faults.
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    A Cluster Algorithm for Uncertain Data Stream
    HAN Dong-hong, WANG Kun, SHAO Chong-lei, MA Chang
    2016, 37 (12):  1677-1682.  DOI: 10.12068/j.issn.1005-3026.2016.12.002
    Abstract ( 572 )   HTML   PDF (525KB) ( 807 )  
    As an important component of big data generated in the sensor, mobile phone devices, social networks etc., uncertain streaming data have many characteristics, such as variable rate, large-scale, single-pass scanning, and uncertainty. Traditional clustering algorithms cannot meet efficient real-time inquiry requirements for the users. Firstly, MBR (minimum bounding rectangle) was used to describe the distribution characteristics of uncertain tuples. And then, a clustering algorithm based on expected distance was proposed for uncertain data stream. The bounds of expected distance range to filter the clusters with far distance can be calculated. Secondly, cluster MBR concept based on the distribution of the tuples in a cluster was presented. Then, a clustering algorithm was given, which excludes the clusters far from the uncertain tuple by the spatial location relationship between uncertainty tuple MBR and clusters MBR, thereby increasing the efficiency of clustering algorithm. Finally, experiments running on synthetic datasets and real datasets verify that the proposed algorithms are effective and efficient.
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    A Consistency Cleaning Method Based on Content-related Conditional Functional Dependencies
    DU Yue-feng, SHEN De-rong, ZHANG Liang, YU Ge
    2016, 37 (12):  1683-1687.  DOI: 10.12068/j.issn.1005-3026.2016.12.003
    Abstract ( 664 )   HTML   PDF (465KB) ( 745 )  
    Based on conditional functional dependencies, content-related conditional functional dependencies (CCFDs) and the consistency cleaning method were presented based on CCFDs. By analyzing the relationship of the conditional functional dependencies, the related conditional functional dependencies were combined into CCFDs. The CCFDs can not only detect the consistencies under multi-conditional values, but also provide reference values for the consistency repairing. A consistency repairing-cost model was presented. Then the data was corrected to be consistent with the minimal repairing cost according to the actual data. And the repaired results are approved accuracy for both the inconsistency detection and the inconsistency repairing via the experimental evaluation on two real-life datasets.
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    Optic-Fiber Sagnac Strain Sensor Based on Alcohol Selectively-Filling Photonic Crystal Fiber
    HU Hai-feng, LI Xue-gang, ZHOU Xue, ZHAO Yong
    2016, 37 (12):  1688-1691.  DOI: 10.12068/j.issn.1005-3026.2016.12.004
    Abstract ( 614 )   HTML   PDF (826KB) ( 871 )  
    A new optic-fiber Sagnac strain sensor based on alcohol filling photonic crystal fiber was proposed and demonstrated, by which measuring the minute strain could be achieved. The birefringence of the photonic crystal fiber (PCF) was produced by alcohol selectively-filling the air holes of the PCF. And then the alcohol selectively-filling photonic crystal fiber was embedded in the Sagnac loop and the Sagnac interference effect was achieved. Then the peak wavelength of the Sagnac interference spectrum could be changed by strain because the peak wavelength shift was directly proportion to strain change. The micro strain sensitivity is measured to be 3.66pm in a micro strain range from 0 to 3958.
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    Research on Fractal Property of Internet
    LI He-qun, XU Jiu-qiang, WANG Jin-fa, ZHAO Hai
    2016, 37 (12):  1691-1695.  DOI: 10.12068/j.issn.1005-3026.2016.12.005
    Abstract ( 609 )   HTML   PDF (783KB) ( 730 )  
    The k-core decomposition algorithm was applied to the study of the Internet fractal property. During the study, the difference of fitting results between high-core region and low-core region was analyzed, and a conjecture was proposed that Internet fractal is related to its hierarchical structure. Subsequently, the k-core decomposition process was observed from three aspects: the number and ratio of deleted edges, and subnets distribution. A partition boundary was found which was useful to distinguish core and periphery, then the Internet fractal hierarchy was studied with the help of the skeleton theory. Finally, relations between part and whole, part and part were observed from degree distribution exponent, assortativity coefficient, and entropy. The observations show that the subnets in the Internet edge can characterize the network from the statistics above.
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    Complex Network Analysis of Pulse Wave
    ZHAO Hai, DOU Sheng-chang, CAI Wei, CHEN Xing-chi
    2016, 37 (12):  1696-1699.  DOI: 10.12068/j.issn.1005-3026.2016.12.006
    Abstract ( 718 )   HTML   PDF (462KB) ( 836 )  
    Pulse wave is one of the important physiological signals in human body. It is an important direction to explore the pulse wave analysis method from the new angle. On the basis of analyzing the existing methods of time domain and frequency domain, the analysis method of complex network was introduced into the analysis of pulse wave to expand the research dimension of pulse wave. Analyzed the present situation of the time series of network method. Horizontal visibility graphs (HVG) network analysis method was used in the analysis of pulse wave network. The characteristic parameters of pulse wave networks were obtained, and the scale-free characteristic of the pulse wave network was determined, which was also be explained in the perspective of physiological state. It provides a new method for the study of pulse wave.
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    Construction of Pest Relationship Network Based on Space Influence Domain and Its Analysis
    WANG Jin-fa, ZHAO Hai, LIU Xiao, LI He-qun
    2016, 37 (12):  1700-1704.  DOI: 10.12068/j.issn.1005-3026.2016.12.007
    Abstract ( 598 )   HTML   PDF (917KB) ( 684 )  
    Network science theory has become an important means to study the significant problems of the ecology. Based on the niches rule and the competitive exclusion principle, a model of space influence domain about the pest was proposed. According to this model, the pest relationship networks of Changbai Mountains were extracted from 2009 to 2013, and then the scale-free of network, important nodes and hierarchy were studied. The statistical results show that out-degree distribution follows a power-law, and the in-degree is well-distributed. The nodes, which exist in all networks and have larger out-degree, have also the larger betweenness value. But the nodes with larger in-degree is high-clustering locally. The hierarchical structure of networks is almost stable. Liaotung peninsula is the high-core area of pest occurring frequently and the most serious area of pest.
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    Automatic Segmentation of Fiducial Marker Based on Sequence Characteristics
    BAO Nan, CUI Zhi-ming, ZHUANG Jin-feng, KANG Yan
    2016, 37 (12):  1705-1709.  DOI: 10.12068/j.issn.1005-3026.2016.12.008
    Abstract ( 678 )   HTML   PDF (658KB) ( 714 )  
    The fiducial markers are widely used for point-pair registration in the image-guided surgery. When performing the registration, the centers of the fiducial markers will be picked. For localization of the fiducial markers, an automatic approach for the segmentation of markers was proposed based on the lung biopsy image-guided surgery system. Firstly, the candidate markers were coarsely segmented from the chest CT image. Then the real markers were detected and confirmed from the candidate markers according to the sequence characteristics approach. Experiments showed that, comparing with the results of manual segmentation, the method can segment the markers with 95% pixel overlap rate and the center localization error is less than 0.22mm.
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    Materials & Metallurgy
    Data Preprocessing and Neural Network Model of C-Mn Steel Based on Big Data
    WU Si-wei, CAO Guang-ming, ZHOU Xiao-guang, LIU Zhen-yu
    2016, 37 (12):  1710-1715.  DOI: 10.12068/j.issn.1005-3026.2016.12.009
    Abstract ( 696 )   HTML   PDF (631KB) ( 843 )  
    In neural network modeling, it may build a wrong model using original data without any treatment or only eliminating the abnormal value, for it could contain the law not to follow the physical metallurgy principle. To make the regularity significant, the original data need to be processed before modeling. In this work, based on the data of the C-Mn steel derived from a large number of data collected from different steel grades, a set of method for data preprocessing was proposed and a model for predicting yield strength of the C-Mn steel was established using LM-BP neural network, which could make the prediction accuracy meet the requirement (94.21%). The effects of the elements content and processing parameters on the yield strength were analyzed by the mean impact value (MIV). The results showed that the yield strength increased with the increase of carbon content and increased with the decrease of final rolling thickness and coiling temperature.
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    Effect of Asymmetric Rolling on Microstructure of AZ31 Magnesium Alloy Sheets
    TANG Yan, LE Qi-chi, JIA Wei-tao, DU De-wang
    2016, 37 (12):  1715-1719.  DOI: 10.12068/j.issn.1005-3026.2016.12.010
    Abstract ( 611 )   HTML   PDF (3357KB) ( 829 )  
    To fullfill the demand of rolling accuracy of magnesium alloy sheets, the symmetric problem during rolling process and the microstructural evolution of the AZ31 sheets with the thickness of 0.5 and 1.0mm, which made by symmetric and asymmetric rolling process using small rollers, were investigated. The results showed that the average grain size in the 0.5mm sheets by symmetric and asymmetric rolling was 10.1 and 8.8μm, respectively, that of the 1.0mm was 16.7 and 13.6μm, respectively. The element equivalent strain of the 0.5mm sheet was up to 0.42 by asymmetric rolling and 0.29 by symmetric rolling and that of the 1.0mm was 0.75 and 0.66, respectively. In symmetric rolling, the distributions of the nodal equivalent Mises stress and shear stress in the 0.5mm sheet were more symmetric by symmetric rolling process, in contrast with those by asymmetric rolling. Grain growth in the 0.5mm sheet by asymmetric rolling was much slower than that by symmetric rolling during annealing for 1h at 250, 300 and 350℃. At 350℃, the average grain size in the 0.5mm sheet by asymmetric rolling was 9.8μm and that by symmetric rolling was 24.9μm.
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    Effects of Reducing Time on Metallization Degree of Carbothermic Reduction of Tall Pellets Bed
    JIANG Xin, WANG Lin, LIU Ming-xu, SHEN Feng-man
    2016, 37 (12):  1720-1725.  DOI: 10.12068/j.issn.1005-3026.2016.12.011
    Abstract ( 543 )   HTML   PDF (1525KB) ( 827 )  
    To explore the operation parameters of the direct reduction processing using the paired straight hearth furnace (PSH), the effects of reducing time on metallization degree of carbothermic reduction of tall pellets bed are investigated in this work. The experimental results show that, when the reducing time is set to 50 and 60min, the metallization degree (MD) of the total pellets bed is 57.31% and 80.23%, respectively. However, there are some disadvantages in the case of 60min, such as re-oxidation of the pellets in the top bed, low heat efficiency, and low productivity. Charging with hot crucible can increase the MD of the pellets, especially for the pellets in the bottom bed. In the case of 50min, the MD of the total pellets bed increases from 57.31% charging with cold crucible to 85.24% charging with hot crucible. Therefore, the hot crucible charge and the 50min of reducing time are suggested for increasing the MD of carbothermic reduction of tall pellets bed, which could provide a guideline for developing the effective reduction process in PSH.
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    Effect of Binary Basicity on Sintering Process and Quality of Indonesia Vanadium Titanium Magnetite
    GAO Qiang-jian, WEI Guo, LIU Chang-sheng, SHEN Feng-man
    2016, 37 (12):  1726-1730.  DOI: 10.12068/j.issn.1005-3026.2016.12.012
    Abstract ( 827 )   HTML   PDF (787KB) ( 752 )  
    Basing on raw materials conditions of typical iron and steel plant, the sintering experiments were carried out for the Indonesia vanadium titanium magnetite under different basicity and the effect of binary basicity (R=m(CaO)/m(SiO2)) on the sintering process and sinter′s quality were investigated in this work. The results showed that when the basicity (R) increased from 1.4 to 2.3, the coefficient of sintering effectiveness decreased from 1.63t/(m2·h) to 1.44t/(m2·h) and the rate of finished products after sintering decreased from 78.5% to 75.3%. Meanwhile, with the increasing of basicity, the vertical sintering speed increased gradually and the w(FeO) decreased constantly. Moreover, with the increasing of basicity from 1.4 to the 2.3, the drum index firstly dropped to the lowest value at the basicity of 1.7 and then rose gradually. With the increase of basicity, both the reduction degradation index (RDI) and reducibility index (RI) could be improved, which help to develop the gas permeability at the top of the furnace and the indirect reduction ability.
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    Physical Simulation of Inclusion Removal by Bubble Trailing Vortex in Liquid Steel
    GENG Dian-qiao, BAO Jin-feng, LEI Hong, HE Ji-cheng
    2016, 37 (12):  1731-1734.  DOI: 10.12068/j.issn.1005-3026.2016.12.013
    Abstract ( 622 )   HTML   PDF (950KB) ( 794 )  
    Based on the equal Morton number and inclusion movement similarity, the polyethylene particle was employed to simulate inclusions in liquid steel. The high speed video-photography was used to record the movement of bubble and inclusion. The mechanism of inclusion removal by bubble trailing vortex was analyzed. The experimental results show that there are two kinds of inclusion trajectories under bubble trailing vortex. One is that the inclusions approach to the bubble trailing vortex under both sides of bubble and enter the bubble trailing vortex zone, then float with a greater velocity before leaving the bubble trailing vortex zone. The other is that the inclusions above the bubble move to the bubble rear in a circuit manner without collision or attachment each other, then float with bubble in the trailing vortex and rise helically along the vertical direction. On the condition of the same floatation distance, the effect of the larger bubble trailing vortex on inclusion removal is better than that of the smaller bubble.
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    Thermodynamic Analysis of Steam Reforming of Tar Component in Raw COG for Hydrogen Production
    XIE Hua-qing, ZHANG Jian-rong, YU Qing-bo, QIN Qin
    2016, 37 (12):  1735-1739.  DOI: 10.12068/j.issn.1005-3026.2016.12.014
    Abstract ( 670 )   HTML   PDF (1002KB) ( 652 )  
    The thermodynamic analysis of the steam reforming of 1-methylnaphthalene as the tar model compound of the raw coke oven gas was carried out using the HSC Chemical software. With the increases of temperature and the steam/carbon (S/C) ratio, the amount and concentration of H2 gradually increased, however their changes became gentle when the temperature passed 500℃ or the S/C ratio was over 8∶1.With the pressure increasing, the H2 amount gradually decreased, therefore the optimal pressure for 1-methylnaphthalene steam reforming was the normal pressure. After CaO was added as CO2 sorbent, the steam reforming reaction process was enchanced, resulting in the significant improvement of the H2 amount and concentration. With the CaO/C ratio of 2∶1 and S/C ratio of 8∶1, the H2 amount and concentration could reach over 95% at the temperature of 400~650℃.
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    High Temperature Modification on Coconut Shell Activated Carbon and Adsorptivity of the Activated Carbon for K+ in Aluminum Electrolyte
    HOU Jian-feng, WANG Zhao-wen, LI Tuo-fu, SHI Zhong-ning
    2016, 37 (12):  1740-1744.  DOI: 10.12068/j.issn.1005-3026.2016.12.015
    Abstract ( 639 )   HTML   PDF (966KB) ( 782 )  
    According to kinetic calculation of adsorption K+ using coconut activated carbon in molten aluminum electrolyte, the modification of the surface properties and the capacity of removing potassium (K+) using the high-temperature modified cocoanut activated carbon were studied, associated with the analysis of SEM, ASAP2000M and FTIR spectrometer. The results showed that the specific surface area changed from 918m2/g to 2544 m2/g after high-temperature modification and the pore size distribution of the adsorbent which exhibited the uniform mesopores were optimized. Meanwhile, the functional group species of activated carbon were not changed after high-temperature modification, which indicated that the structure of high-temperature modification activated carbon could keep stable in molten aluminum electrolyte. For the capacity of removing K+, it was found that the adsorption kinetics process could be described using the pseudo-second-order model and the adsorption equilibrium was reached after 35 minutes with the maximum adsorption capacity of K+ of 20.8mg/g.
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    Mechanical Engineering
    Analysis on Crack Tip J Integral Value Under Sliding Contact Effect
    YAN Yu-tao, QIAN Xiao-lin, ZHANG Yi-bo, SUN Zhi-li
    2016, 37 (12):  1744-1749.  DOI: 10.12068/j.issn.1005-3026.2016.12.016
    Abstract ( 593 )   HTML   PDF (978KB) ( 692 )  
    The influence of sliding contact effect on crack tip J integral value was investigated by fracture mechanics and finite element analyses under dry friction. The variation regulation of crack tip J integral value under different friction coefficient, contact pressure, crack length and crack modality was obtained. The results show that the variation of crack tip J integral value is different with crack modality while the friction effect is considered. The increasing of friction effect aggravates variation of the crack tip J integral value for vertical crack. For oblique crack, the increasing of friction effect weakens variation of the crack tip J integral value in the vicinity of sliding to crack. The fluctuation range of crack tip J integral value increases with contact pressure increasing. The smaller the included angle between the direction of the sliding velocity and the crack, the more significantly the crack tip J integral value changes under the same contact pressure and frictional effects. The J integral value first increases and then decreases as the crack deepens.
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    Control Strategy of Regenerative Braking for Plug-in Parallel Hybrid Electric Vehicles
    CHEN Ze-yu, YANG Ying, WANG Xin-chao, LYU Ming
    2016, 37 (12):  1750-1755.  DOI: 10.12068/j.issn.1005-3026.2016.12.017
    Abstract ( 696 )   HTML   PDF (750KB) ( 1440 )  
    Different from traditional internal combustion engine vehicles, hybrid electric vehicles (HEVs) have regenerative braking capability to improve fuel economy. Taking a plug-in parallel HEV with axles torque coupling as the research object, the influences of regenerative braking were analyzed. A regenerative braking control strategy using fuzzy control was then proposed. The presented strategy was to make two-layers control decision. The braking torque was allocated between the front axle and rear axle in the top layer, while the algorithm in bottom layer split the rear axle braking torque between mechanical braking and electric braking. The strategy was evaluated in a simulation study using several typical driving cycles. The results show that the as-proposed fuzzy control strategy can significantly improve the effect of energy recovery up to 23.44%, compared with that of the traditional ideal braking force distribution curve strategy.
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    Sealing Capability and Parameter Optimization of Screw Seal
    REN Zhao-hui, WEI Jie-tao, LI Yong-chao, XU Yu-hang
    2016, 37 (12):  1755-1758.  DOI: 10.12068/j.issn.1005-3026.2016.12.018
    Abstract ( 762 )   HTML   PDF (622KB) ( 948 )  
    A spiral sealed liquid capacity model was established for fluid motion under laminar flow conditions. Using the CFD method, the stress distribution of the seal material and sealing medium speed differential force distribution under the pressure gradient force were analyzed, and thus to obtain pumping rate and the annular lower leakage flow along the helical groove and differential pressure pumping gap leakage. According to the flow equilibrium theory, the sealing parameters were obtained and the spiral sealing structure parameters were optimized. The sealing capacity is strongest in the case of the ratio of tooth top width and space width, gullet depth and gap as well as the angle of helix are 1, 2.61 and 15.6°, respectively. Reference was provided for the selection of spiral seal structure parameters under laminar flow conditions.
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    Quantitative Identification of Microcracks Through Magnetic Flux Leakage Based on Improved BP Neural Network
    QIU Zhong-chao, ZHANG Wei-min, ZHANG Rui-lei, MA Chun-hong
    2016, 37 (12):  1759-1763.  DOI: 10.12068/j.issn.1005-3026.2016.12.019
    Abstract ( 511 )   HTML   PDF (572KB) ( 726 )  
    Magnetic flux leakage detection is one of NDT methods for ferromagnetic materials. Quantitative identification is to identify the crack size through obtaining magnetic flux leakage signals. By combining principal component analysis (PCA) and neural network, a model was established to predict width and depth of the micro crack. The principal component analysis removed the data correlation and reduced the dimension of the input samples, so it can significantly simplify the network structure. BP neural network optimized by genetic algorithm (GA-BP neural network) can prevent the search process from running into the local optimal solution. Based on the theoretical calculation of magnetic dipole model and experiment on the artificial cracks, the algorithm applied in the quantitative recognition of microcracks was verified, which may lay the foundation for the early quantitative recognition technique of crack development stage.
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    Resources & Civil Engineering
    Grinding Kinetics of Anshan Type Hematite Ores in a Ball Mill
    CAO Jin-cheng, LIU Lei, HAN Yue-xin
    2016, 37 (12):  1764-1768.  DOI: 10.12068/j.issn.1005-3026.2016.12.020
    Abstract ( 600 )   HTML   PDF (388KB) ( 662 )  
    Grinding specific rate of Anshan type hematite ores was analyzed using MATLAB software. Test results showed that breakage of ore particles in the grinding process went through three inherent stages: rapid grinding of coarse size fraction, dynamic grinding of middle size fraction and single grinding of middle size fraction. Particles in 0.043~0.031mm size fraction went into dynamitic grinding stage earlier than particles in 0.105~0.043mm size fraction, and then overgrinding of fines occurred easily in ball mill. Compared with cone crusher products, HPGR (high pressure grinding rolls) products had significantly shorter turning time points in three breakage stages, which means that HPGR products were ground faster with earlier occurrence of overgrinding. Given this, the increase of HPGR product tonnages into mills shortened the residence time of materials in ball mill, not only improving the capacity of mineral processing plants but also weakening overgrinding of fines.
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    Theoretical Model and Experimental Study on the Ignition of Oil Shale Dust Layer
    YANG Hong-xia, LI Gang, YUAN Chun-miao, YU Li-fu
    2016, 37 (12):  1768-1771.  DOI: 10.12068/j.issn.1005-3026.2016.12.021
    Abstract ( 712 )   HTML   PDF (468KB) ( 712 )  
    In order to study the fire risk of oil shale dust, an asymmetric model of dust layer ignition under steady-state condition was established by using chemical reaction kinetics, heat transfer and Thomas thermal ignition theory. The minimum ignition temperature of dust layer of 4 oil shale samples from the major producing areas of China was tested. The results showed that the minimum ignition temperature is between 503~613K, and it decreases with the increasing layer thickness. The minimum ignition temperature order of the four samples is as follows: Fushun> Huadian> Longkou> Maoming, which is correlated reciprocally with volatile content. Using the theory model, the activation energy and critical ignition temperature corresponding to different thickness were calculated. It was found that the error between the calculation critical ignition temperature and experimental results is within 10%, which provides a feasible method on theoretical prediction of fire risk in the oil shale production process.
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    Experimental Investigation on Axial Compression Behavior of Channel Columns with Complex Edge Stiffeners and Cap Shaped Stiffeners
    SONG Bo, WANG Lian-guang, WANG Chun-gang
    2016, 37 (12):  1772-1777.  DOI: 10.12068/j.issn.1005-3026.2016.12.022
    Abstract ( 519 )   HTML   PDF (1263KB) ( 588 )  
    A total of 18 simply supported axial compression members with three types of complicated sections were tested. The bearing capacity, buckling mode and deformation behavior of these members were studied. The results show that cap shaped stiffeners can increase the ultimate load-carrying capacity of loaded members obviously. Compared with channels with complex edge stiffeners under the same condition, members with cap shaped stiffeners can make the ultimate load-carrying capacity be increased about 10% to 40%. Distortional and local interaction buckling became the main buckling modes. Numerical simulations were performed by finite element analysis. The analysis results are in good agreement with experimental data.
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    Model of Loosen Blasting Assisted by High-Pressure Water Jet Spiral-Notch
    SU Deng-feng, KANG Yong, WANG Xiao-chuan, ZHENG Dan-dan
    2016, 37 (12):  1778-1783.  DOI: 10.12068/j.issn.1005-3026.2016.12.023
    Abstract ( 601 )   HTML   PDF (1092KB) ( 765 )  
    A new technology of loosen blasting assisted by high-pressure water jet spiral-notch was put forward based on its unique advantages of water jet cutting, and the geometric model for water jet notched boreholes was established based on experiments. Furthermore, by employing fracture mechanics and Westergaard stress function method, the functions of complex variables was confirmed, and the stress field acted upon the spirally water jet notching borehole by quasi-static explosion gas was derived. The stress intensity factor of spiral-notch boreholes with high-pressure water jet was determined, and the loosening effect of loosen blasting assisted by high-pressure water jet spiral-notch was also analyzed. Finally, ANSYS/LS-DYNA was applied to verify the theoretical model, and the results of the numerical simulation are almost comparable to the model.
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    Research and Application of Three-Dimensional Scattered Points Modeling Technology in Complex Cavity
    HUANG Jun-jie, LUO Zhou-quan, QIN Ya-guang, ZHANG Wen-fen
    2016, 37 (12):  1784-1788.  DOI: 10.12068/j.issn.1005-3026.2016.12.024
    Abstract ( 533 )   HTML   PDF (1002KB) ( 789 )  
    Aiming at scattered data, a set of equally spaced cutting face in vertical direction of maximum bounding box was used to segment scattered point cloud, and the method of cavity three-dimensional model was proposed by taking cavity three-dimensional laser scanning system to obtain original data as the basis. The direction and pitch of parallel cutting surface was determined firstly to divide and cut scattered point cloud. Then the location of scattered point cloud which is in cutting surface was determined by the minimum distance method. Finally, scattered points were sorted through convex hull the minimum distance method, and it was modeled after becoming ordered points. Applications show scattered points modeling algorithm of complex cavity is accurate, which can be realized in complicated scattered point cloud modeling.
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    Experimental Study on the Determination Method of σcc,σci and σcd for Granite Under Different Confining Pressures
    CHEN Shi-wan, YANG Chun-he, WANG Gui-bin , WEI Xiang
    2016, 37 (12):  1789-1794.  DOI: 10.12068/j.issn.1005-3026.2016.12.025
    Abstract ( 750 )   HTML   PDF (706KB) ( 670 )  
    The determination of the stress thresholds of crack closure (σcc), crack initiation (σci) and crack damage (σcd ) of rock is of great significance for understanding the progressive failure process of rock from high-level radioactive geological waste repository. The Brazilian test and triaxial compression test are performed to determine those stress thresholds. Three methods including moving point regression technique, crack volumetric strain and acoustic emission hits rate are applied to determine these thresholds mentioned above. A comprehensive method is proposed to determine stress thresholds accurately and conveniently. The relationship of various thresholds and corresponding confining pressure are also analyzed, results show that σcc is less sensitive to confining pressure compared with the crack damage stress σcd, the crack initiation strength(σci) meets Griffith strength theory, which is confirmed by the tensile strength from Brazilian test.
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    Experimental Study of One-Dimensional Thermal Consolidation of Saturated Clays
    ZHANG Yu-ning, CHEN Yu-long, LI Bo
    2016, 37 (12):  1794-1799.  DOI: 10.12068/j.issn.1005-3026.2016.12.026
    Abstract ( 664 )   HTML   PDF (825KB) ( 915 )  
    The consolidation properties of two saturated clays were studied by laboratory tests under different temperatures. Results showed that: the effect of temperature on the expansion of soil particles and the contraction of void ratio was small; high temperature induced thermal expansion could affect the deformation to some extent, so the compression index became smaller as the temperature increased. However, such an effect diminished due to better permeability; the pre-consolidation stress decreased with increasing temperature. The material parameter γ for two clays was calculated by back analysis. The clay with larger γ had smaller normalized pre-consolidation stress under the same temperature; the higher temperature led to less excess pore water pressure due to higher permeability coefficient because the viscosity of pore water at higher temperatures became weaker. It was found that the permeability coefficient increased with larger void ratio and grain size.
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    Debris Flow Susceptibility Analysis Based on Relative Difference Function and Game Theory
    RUAN Yun-kai, CHEN Jian-ping, SHI Ming-yuan, LI Yan-yan
    2016, 37 (12):  1800-1804.  DOI: 10.12068/j.issn.1005-3026.2016.12.027
    Abstract ( 479 )   HTML   PDF (1473KB) ( 795 )  
    A relative different function of the variable fuzzy theory was introduced to the building of a sensitivity analysis model for debris flow. 11 debris flow catchments located in Chifeng pumped storage power station in Inner Mongolia were investigated. Seven major factors, namely, loose material volume per square kilometer, loose material supply length ratio, average gradient of the main channel, average hill slope, drainage density, curvature of the main channel, and poor vegetation area ratio, were selected for debris flow susceptibility analysis. Precedence chart was used for objective weighting and entropy method was used for subjective weighting. Combination weighting was calculated by game theory. Combination weights of major factors for the investigated 11 debris flow catchments are 0.19, 0.14, 0.19, 0.10, 0.09, 0.18 and 0.11, respectively. Susceptibility results show that the susceptibility of 6 debris flow catchments are very low and 5 are low. Comparing the susceptibility results with field observations, 11 debris flow catchments agrees very well with real status of debris flow, proved the feasibility of this method.
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