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15 November 2018, Volume 39 Issue 11 Previous Issue    Next Issue
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Information & Control

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Steelmaking Continuous Casting Ladle Matching Method Based on Rule-Learning LIU Wei， CHAI Tian-you 2018, 39 (11):  1521-1526.  DOI: 10.12068/j.issn.1005-3026.2018.11.001 Abstract ( 801 )   HTML   PDF (388KB) ( 836 )   In steelmaking-continuous casting ladle matching， the ladle properties are numerous and the targets are difficult to meet at the same time. The performance indicators are established by first-order rule-learning to maximize the ladle temperature and ladle use times， minimize the ladle material grade and nozzle number. The ladle temperature， life， material， nozzle， skateboard and frame use times are constraints. The selection rules of ladle are given by minimal generalization method. The method of heuristic ladle selection based on rule priority is proposed. The actual data simulation and applying results show that the proposed method can improve the production efficiency and the number of online ladle and ladle maintenance per day can be reduced. References | Related Articles | Metrics

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DC-Offset Elimination Method for Grid-Connected Phase-Locked Loop by Modified DSC HUI Nan-mu， WANG Da-zhi， LI Yun-lu 2018, 39 (11):  1526-1531.  DOI: 10.12068/j.issn.1005-3026.2018.11.002 Abstract ( 781 )   HTML   PDF (651KB) ( 799 )   The use of delay signal cancellation(DSC)operator in the control inner loop of SRF-PLL slows down the dynamic behavior. A fast DC-offset rejection method for three-phase PLL of grid synchronization is proposed， which improves the dynamic performance of traditional DSC-based PLL by using the modified DSC operator. This method can effectively overcome the influence of the system bandwidth on the DC-offset elimination and improve the response speed of the system. In addition， the adjustment time of the phase jump and frequency step change based on the MDSC-based PLL is also very small. The effectiveness of the proposed method is confirmed through simulation and experiment results. References | Related Articles | Metrics

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Low-Delay Coding-Aware Routing Algorithm Based on Time Threshold Value GENG Rong， SUN Xue-chao， WANG Meng-yuan， CHEN Wen-jun 2018, 39 (11):  1532-1535.  DOI: 10.12068/j.issn.1005-3026.2018.11.003 Abstract ( 704 )   HTML   PDF (414KB) ( 609 )   Existing coding aware routing algorithms ignore a realistic question that different data packets reach the encoding node at different time. To overcome the above problem， an improvement scheme was proposed using a threshold value on the basis of existing coding-aware routing. Firstly encoding condition was used to find the nodes to encode. Then the network delay training phase was introduced to obtain the threshold value of waiting time. Lastly， it was decided whether to wait or not according to the relationship between the actual value and the threshold value. Simulation results show that the algorithm can achieve a better result than the traditional opportunistic coding policy in delivery delay and throughput. References | Related Articles | Metrics

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Entity Alignment Algorithm for Knowledge Graph of Representation Learning ZHU Ji-zhao， QIAO Jian-zhong， LIN Shu-kuan 2018, 39 (11):  1535-1539.  DOI: 10.12068/j.issn.1005-3026.2018.11.004 Abstract ( 2813 )   HTML   PDF (394KB) ( 2026 )   A novel supervised method for knowledge graph entity alignment based on representation learning was proposed， which is different from the existing methods due to the similarity of structural information or attributive characters. First， the method automatically learns the semantic representations for the entities and relations of a knowledge graph in a low-dimensional vector space was proposed， and these embeddings contain the intrinsically structural information of a knowledge graph and the attributive features of entities. Afterwards， taking the manually aligned entity pairs as prior knowledge， the cross-KG mapping relationship between entities could be learned， which will be used for predicting entity alignment. Experiments conducted on real datasets demonstrated that our method can effectively improve the precision of knowledge graph entity alignment while keeping a high F1 score， when compared with the feature matching based method SiGMa. References | Related Articles | Metrics

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Characteristic Analysis of Gold-Coated Photonic Crystal Fiber Polarization Filter YAN Xin， WANG Hai-yang 2018, 39 (11):  1540-1544.  DOI: 10.12068/j.issn.1005-3026.2018.11.005 Abstract ( 650 )   HTML   PDF (1162KB) ( 819 )   A photonic crystal fiber polarization filter based on surface plasmon resonance is proposed and investigated. The gold is coated into the selected air holes in order to make surface plasmon modes and core modes resonate. The finite element method is used to analyze the effect on the filter performance by changing the parameters. Numerical simulation results show that the positions of resonance peaks and the resonance strength of core mode and surface plasmon mode can be well adjusted by changing the thickness of gold film and diameter of air holes. The confinement loss in x-polarization can reach to 740.5dB/cm at 1.31μm， the confinement loss in y-polarization is very low， and the loss peaks in x-polarization and y-polarization are separated by a large distance. Then a novel kind of photonic crystal fiber polarization filter working at the communication wavelength is designed. References | Related Articles | Metrics

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Shape Modeling of Pulmonary Nodules Based on Fractal Dimension Characteristic ZHAO Hai， LI Xiong-feng， ZHU Hong-bo， WANG Bin 2018, 39 (11):  1545-1551.  DOI: 10.12068/j.issn.1005-3026.2018.11.006 Abstract ( 848 )   HTML   PDF (873KB) ( 723 )   Aiming at the modeling of pulmonary nodule shape， a new method to model the shape of pulmonary nodules based on the fractal dimension characteristic of complex networks was proposed. Firstly， the Euclidean distance between the sampling points on the shape contour is modeled by network， then the network is dynamically evolved with LBP(local binary patterns) values， and the complexity of the complex network is analyzed by using the fractal dimension. Compared with the traditional shape modeling method， the proposed method not only considers the local texture feature shape and improves the anti-interference ability to resist non-rigid shape deformation， but also improves the efficiency of modeling with no need of sample shape alignment. Based on the LIDC-IDRI database and the CT data of Shengjing hospital of Shenyang， simulation experiments show that this method performs well on shape model of pulmonary nodules. References | Related Articles | Metrics

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Topological Characteristic Analysis of Weighted Seismic Network Based on Space-Time Influence Domain XU Yan-jie， REN Tao， QI Yi 2018, 39 (11):  1551-1555.  DOI: 10.12068/j.issn.1005-3026.2018.11.007 Abstract ( 610 )   HTML   PDF (443KB) ( 673 )   The seismic network of the south California is taken as the research object. In order to study the influence relationship among nodes in seismic network， the weighted seismic network is generated based on the space-time influence domain and the mean magnitude ratio. Then， based on the reference effect of null model， the topological characteristic of weighted seismic network is analyzed. At the same time， the weight distribution of the edge and the node are analyzed. It is found that the weighted seismic network has scale-free and small-world characteristics， and both the node and the edge weight have power-law distribution. In addition， there is a positive correlation between the weight of the node and its maximum magnitude. Based on the seismic data， the weighted seismic network can reflect the actual situation well. References | Related Articles | Metrics

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Generative Adversarial Networks for the Classification of Lung Nodules Malignant XU Jiu-qiang， HONG Li-ping， ZHU Hong-bo， ZHAO Hai 2018, 39 (11):  1556-1561.  DOI: 10.12068/j.issn.1005-3026.2018.11.008 Abstract ( 883 )   HTML   PDF (613KB) ( 947 )   In order to solve the proportion of benign and malignant lung nodule， a novel model named deep convolutional generative adversarial networks(DCGAN) was introduced. The model generates lung nodule images with similar texture feature from the input lung nodules images， and then using them to train the DCGAN model. In addition， the classification of image source is changed to the classification of image source and lung nodules grade 1~5. thus， the noise immunity of DCGAN model is enhanced and the classification of lung nodules by DCGAN model is realized. Experiments show that the model G in improved DCGAN enhances the performance of anti-noise capability with 90.42% images are distinguished true images when it generating images， and the model D has a good discriminant ability for the classification of lung nodule images and the classification accuracy of lung nodules is 70.89%， the recognition rate of malignant lung nodules is 80.13%. References | Related Articles | Metrics

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Modify and Integrate Lung Segmentation Algorithm DOU Sheng-chang， ZHAO Hai， ZHU Hong-bo， WANG Bin 2018, 39 (11):  1562-1566.  DOI: 10.12068/j.issn.1005-3026.2018.11.009 Abstract ( 663 )   HTML   PDF (778KB) ( 729 )   In order to obtain better segmentation results under acceptable computational complexity， the advantages and disadvantages of the existing methods are summarized， and then the lung segmentation method which modifies and integrates the simple methods is proposed. Firstly， the clustering method is used to classify the pixels in CT images into two categories， and the small regions with different gray values are obtained. And then the initial region of the lung is identified. Finally， according to the specific characteristics of the CT image， the boundary is corrected by using the gradient and the gray information of the pixels near the initial lung boundary. The processing results of CT images using the above synthesis method show that the segmentation results can be better when the computational complexity is not too large. References | Related Articles | Metrics

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Generative Models of Human Brain Functional Networks Based on Local Community SI Shuai-zong， LIU Xiao， ZHU Jian， ZHAO Hai 2018, 39 (11):  1566-1571.  DOI: 10.12068/j.issn.1005-3026.2018.11.010 Abstract ( 623 )   HTML   PDF (731KB) ( 670 )   The effects of both regional topological structures and anatomical structures on human brain functional networks modeling were investigated， and generative models of human brain functional networks based on local communities were proposed. The local community topologies of the models are measured by not only the common neighbors between the two functional regions but also the connections among the neighbors. And the anatomical structures are represented by the anatomical distance between the two brain regions. In addition， the similarity energy index was proposed to evaluate the similarity between the generated network and the real data network based on functional magnetic resonance images(fMRI). The results show that the generative models based on local communities provide a good fit to the real data network in terms of network efficiency， clustering coefficient， modularity and degree distribution compared with traditional generated models. References | Related Articles | Metrics

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Automatic Detection of Left Ventricular Ejection Fraction Based on Fully Convolutional Networks XU Li-sheng， ZHANG Shu-qi， NIU Xiao， XU Yang 2018, 39 (11):  1572-1576.  DOI: 10.12068/j.issn.1005-3026.2018.11.011 Abstract ( 883 )   HTML   PDF (543KB) ( 829 )   An automatic estimation method of left ventricular ejection fraction based on fully convolutional networks(FCN)is proposed. The left ventricle in magnetic resonance images(MRI) of heart is segmented using FCN. Furthermore， the volume of left ventricle can be calculated at each phase in a heart beat cycle. Finally， the volume of end-systolic and end-diastolic are extracted respectively to deduce the left ventricular ejection fraction. 700 sets of images are used for training the networks and 400 sets for testing. The final results agree well with the ejection fraction(EF)gold standard provided by the American National Institutes of Health and Children′s National Medical Center. The accuracy of the proposed method achieves 89.8%， which is within an acceptable range. References | Related Articles | Metrics

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Segmentation of Left Ventricle Endocardium Based on Transfer Learning of Fully Convolutional Networks QI Lin， LYU Xu-yang， YANG Ben-qiang， XU Li-sheng 2018, 39 (11):  1577-1582.  DOI: 10.12068/j.issn.1005-3026.2018.11.012 Abstract ( 822 )   HTML   PDF (928KB) ( 871 )   To avoid the over-fitting phenomenon， a segmentation method of left ventricle endocardium based on transfer learning of FCN was proposed. The VGG network which had been trained through the natural images was fine-tuned. In addition， some segmentation criteria were employed to optimizing the results based on the priori information that the left ventricle endocardium was in the center of the MRI(magnetic resonance imaging). In the end， 45 cases taken from the 2009 MICCAI dataset was tested by this mothod. The computed DICE index， APD and GC ratio were 0.91， 1.73mm and 97.81%， respectively. Better results in segmentation of left ventricle endocardium were achieved through the transfer learning of fully convolutional networks and the priori information can improve the automatic segmentation results. References | Related Articles | Metrics

Materials & Metallurgy

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Effect of Inter-Pass Cooling Process on Microstructure and Properties of Ultra-heavy Steel Plate WU Jun-yu， WANG bin， WANG Bing-xing， WANG Zhao-dong 2018, 39 (11):  1582-1587.  DOI: 10.12068/j.issn.1005-3026.2018.11.013 Abstract ( 736 )   HTML   PDF (3564KB) ( 755 )   By using a cooling device beside the laboratorial rolling mill， an inter-pass cooling(IPC) process was applied during rolling ultra-heavy steel plate. Here， the effect of the IPC process on microstructure and properties of the rolled plate was studied. The results showed that the steel plate has excellent strength and toughness after the IPC process. When the rolled plate is applied by a strong IPC process， the grain size is 10μm， the strength is 376MPa and the impact energy at -40℃ is 169J at the 1/4-thickness， while they become 15μm， 360MPa and 123J respectively at the 1/2-thickness. Meanwhile， a surface ultra-fine grain layer with the thickness of 470μm can be obtained and the average grain size is less than 5μm. The strength and toughness of the rolled plate are better in a strong IPC process than those in the inter-slab cooling process. When the intensity of the IPC process increases， the grain size decreases and the strength increases. References | Related Articles | Metrics

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Effect of Online-Cooling on Microstructure and Mechanical Properties of Hot-Rolled L360 Steel Pipe LI Zhen-lei， CHEN Dong， KANG Jian， YUAN Guo 2018, 39 (11):  1588-1592.  DOI: 10.12068/j.issn.1005-3026.2018.11.014 Abstract ( 720 )   HTML   PDF (3230KB) ( 625 )   In the view of the hot-rolled seamless steel pipe problems which lacks the way to control microstructure and mechanical properties， depends on the addition of alloying element excessively and uses an off-line heat treatment， an online cooling after rolling treatment is used to replace off-line treatment by means of the plate rolling instead of tube rolling. The effects of different cooling strategy on the microstructure and mechanical properties of a typical hot-rolled L360 steel pipe is studied. The results show that compared with air cooling treatment which easily causes a coarse Widmanstatten structure in L360 steel， the cooling after rolling treatment can promote the precipitation of microalloying elements， refine Widmanstatten structure and improve mechanical properties of the steel. When cooling temperature is controlled at 650℃， the formation of Widmansatten structure is reduced effectively and the balance of strength， toughness and plasticity of L360 steel can be achieved with the yield strength of 478MPa， the tensile strength of 641MPa， the elongation of 25.3%， the yield ratio of 0.74 and the impact energy at 0℃ of 164J， respectively， which meet the requirements of the standard of API SPEC 5L—2012. References | Related Articles | Metrics

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Fabrication of Ultrafine-Grained Gradient Cemented Carbide by SPS Pre-sintered Method XU Zhi-feng， ZHOU Xiang-kui， WANG Kai， WANG Qiang 2018, 39 (11):  1593-1597.  DOI: 10.12068/j.issn.1005-3026.2018.11.015 Abstract ( 779 )   HTML   PDF (3427KB) ( 772 )   The ultrafine-grained gradient cemented carbide (UGCC) was prepared by a two-step sintering， containing spark plasma or vacuum pre-sintering， and a gradient sintering. The effect of the pre-sintering mode (spark plasma or vacuum)on microstructure of the UGCC is studied and the influence of the pre-sintered microstructure on the gradient formation and grain growth during gradient sintering process is also analyzed. The results show that the pre-sintered microstructure of the UGCC greatly affects the gradient formation and grain growth during gradient sintering. Using this two-step sintering， the thickness of gradient layer of the UGCC can be increased to 53μm， associated with the average grain size of WC about 0.3μm. References | Related Articles | Metrics

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Effect of Co Content on Microstructure and Mechanical Properties of CB2 Steel MA Yu-lin， ZHANG Li-ping， LIU Yue， LIU Xing-gang 2018, 39 (11):  1598-1603.  DOI: 10.12068/j.issn.1005-3026.2018.11.016 Abstract ( 753 )   HTML   PDF (3610KB) ( 782 )   In order to study the effect of Co content on microstructure and mechanical properties of the CB2 steel， the contents of Co in CB2 steel were adjusted to 0.5%， 1%， 1.5%， 2% and 3%， respectively. Using optical microscope (OM)， scanning electron microscopy (SEM)， and tensile test at room temperature， the effect of different Co content on the microstructure and mechanical properties was studied， associated with the Thermo-Calc and JMatpro-7.0 simulations. It is found that when the content of Co in the steel increases， the chromium equivalent value increases and the δ-ferrite content decreases. Especially， when the content of Co is 1.5%， the δ-ferrite is appears. Meanwhile， with the increase of Co content， the tensile strength of the steel increases， while the elongation increases firstly and then decreases. The results indicate that the steel with the Co content of 1.5%has a good comprehensive property， where the ultimate tensile strength reaches 805.13MPa， and the elongation is 20.4% and Brinell hardness is 260， respectively. References | Related Articles | Metrics

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Effect of Mean Taylor Vortex Motion on Turbulent Fluctuations in the Presence of Axial Magnetic Field LENG Xue-yuan， LI Ben-wen， WANG Wei， TIAN Xi-yan 2018, 39 (11):  1604-1608.  DOI: 10.12068/j.issn.1005-3026.2018.11.017 Abstract ( 736 )   HTML   PDF (536KB) ( 633 )   The direct numerical simulation based on the current density conservative scheme was employed to calculate the turbulent Taylor-Couette flow of an electrically conducting fluid in an axial magnetic field. The generation of negative velocity due to the interaction of magnetic field with induced current， and the effect of magnetic field on the mean flow field were revealed， when two cylinders had the same potentials. By using two kinds of averaged method， the total fluctuations in the flow field were divided into two parts，i.e.， the contribution of mean Taylor vortex flow and the contribution of turbulence. Consequently， several cases were calculated to investigate the effect of magnetic field on the contribution， and comparation the effects of axial magnetic field on from mean Taylor vortex flow and the turbulent flow. References | Related Articles | Metrics

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Feasibility Study on Heat Recovery of Converter Gas by Honeycomb Heat Regenerator QIN Qin， WANG Kui-ming， YU Qing-bo， FANG Lin 2018, 39 (11):  1608-1613.  DOI: 10.12068/j.issn.1005-3026.2018.11.018 Abstract ( 663 )   HTML   PDF (763KB) ( 647 )   Based on the ignition energy of the converter gas， the safety of waste heat recovery from converter gas at middle and low temperature in the honeycomb regenerator is analyzed. A physical model of the channel in the honeycomb regenerator is established. Potential total energy of multi-particle phase in the honeycomb regenerator is calculated by using JKR collision theory and the theory of tribology. Based on the minimum ignition energy(MIE) of converter gas through the MIE experiment platform at room temperature， the experimental correction calculation formula of MIE is revised and the modified coefficient is 0.909.The MIE in three kinds of converter gas at the ignition temperature of 973K is 7.36×10-7，6.26×10-7 and 6.01×10-7J， respectively. Compared with the potential ignition energy， the results show that it is safe and feasible to recover the waste heat from the converter gas at medium-low temperature in the honeycomb regenerator when the bore diameter is smaller than 6mm. References | Related Articles | Metrics

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Experimental Study on Calcification Process of Diaspore Bayer Red Mud XIE Li-qun， ZHANG Ting-an 2018, 39 (11):  1614-1618.  DOI: 10.12068/j.issn.1005-3026.2018.11.019 Abstract ( 1383 )   HTML   PDF (687KB) ( 1055 )   Large scale utilization of high alkalinity red mud generated in Bayer process is becoming a worldwide problem. Aiming at this problem， a novel calcification-carbonation process is proposed. Firstly， red mud was treated with lime， where the silicon phase is converted into hydrogarnet and alkali is removed. Then， calcification residue is decomposed by CO2 and alumina is recovered. The effect of calcification temperature， Ca-Si molar ratio， and liquid-solid ratio on alkali content in calcification process were investigated. The results indicate that the w(Na2O)in red mud reduces from 6.70% to 0.35% at reaction temperature of 160℃， Ca-Si molar ratio of 2.5∶1， liquid-solid ratio of 3∶1. Moreover， the XRD results show that diffraction peak of the alkali in red mud disappears after the calcification transformation， and hydrogarnet is the main phase. References | Related Articles | Metrics

Mechanical Engineering

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Natural Frequency Analysis and Verification of Fiber-Reinforced Composite Beams with Non-overlapping Delaminations XU Zhuo， LI Hui， XUE Peng-cheng， WEN Bang-chun 2018, 39 (11):  1619-1623.  DOI: 10.12068/j.issn.1005-3026.2018.11.020 Abstract ( 735 )   HTML   PDF (743KB) ( 651 )   Firstly， according to the anisotropic characteristics of composite beams， the vibrational function of each sub beam was expressed by substructure analysis method， and the theoretical solution principle of the natural frequency of composite beams was clarified. Secondly， based on Matlab software， an analysis process of the natural frequency was proposed and the calculation program was coded . Finally， an experimental application toward TC500 carbon fiber/resin matrix composite beam was carried out， that the natural frequencies of fiber-reinforced composite beam with non-overlapping delaminations were measured under the same boundary condition based on the established natural frequency test system. It was found that the natural frequencies decreases gradually as the delamination number increasing. Meanwhile， with the increase of modal orders， the influence of delaminations on the natural frequencies became more obvious. Furthermore， the related errors were within the range of 1.06%~ 5.49% by comparing experimental results with calculated results， which have verified the validity of the analysis method. References | Related Articles | Metrics

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Dynamic Analysis of the Hard-Coating Mistuned Blisk Using ROM GAO Feng， SUN Wei， FAN Yun-fei 2018, 39 (11):  1624-1629.  DOI: 10.12068/j.issn.1005-3026.2018.11.021 Abstract ( 656 )   HTML   PDF (796KB) ( 666 )   A damping vibration reduction method with depositing hard coating on blades was proposed， and a mistuned blisk with NiCoCrAlY+YSZ hard coating deposited was taken as example for numerical calculation. Firstly， the reduced-order model (ROM) of the hard-coating mistuned blisk was established by the improved fixed interface component modal synthesis method (Fixed-ICMSM)， then the vibration characteristics were calculated. Subsequently， the influences of hard coating were studied toward vibration characteristics of the mistuned blisk. Next， the influence of the coating thickness was studied particularly toward damping capacity of mistuned blisk. The results revealed that the NiCoCrAlY+YSZ hard coating has little effect on natural frequencies and good effect on damping. Also， the resonant response of the mistuned blisk can be suppressed remarkably， by the hard coating. References | Related Articles | Metrics

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Milling Force Coefcient Identication for Multi-axis and Ball-End Milling Cutter WANG Bo， LI Bai-chun， YANG Jian-yu， WANG Wan-shan 2018, 39 (11):  1630-1635.  DOI: 10.12068/j.issn.1005-3026.2018.11.022 Abstract ( 1096 )   HTML   PDF (1266KB) ( 1043 )   A new method for the identification of milling force coefficients is proposed for the prediction of the milling forces in multi-axis milling with ball-end cutter. Firstly， the shearing coefficients of milling forces are fitted with multiple order polynomial function of axial position angle， the identification model is derived based on average milling forces as well as the milling force model of multi-axis ball-end-cutter milling. Secondly， the experiment plan of multiple group slot milling for milling coefficient identification is presented， in which the groups are distinguished from each other by varying the angle between the cutter axis and the work piece surface in the slot milling. This experiment is used to ensure the identified coefficients contain the effect factor of different cutter postures. Finally， the proposed method is validated experimentally and the results show that the proposed method is better than that based on instantaneous milling forces in terms of anti-interference and identification precison. References | Related Articles | Metrics

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Path Synthesis Optimal Design of Pick-Up Manipulator Based on Modified Particle Swarm Optimization HUANG Qiu-jun， ZHANG Kai， SONG Jin-chun， YU Zhong-liang 2018, 39 (11):  1636-1641.  DOI: 10.12068/j.issn.1005-3026.2018.11.023 Abstract ( 863 )   HTML   PDF (568KB) ( 806 )   To optimize the motion curve for the pick-up manipulator when going into the mold， an novel method called quadratic Lagrange interpolation particle swarm optimization(QLIPSO)algorithm which can expand the search space， prevent premature convergence， and improve the convergence accuracy effectively is proposed. To verify the effectiveness of QLIPSO， four modified PSO algorithms are compared to synthesize the four-bar linkage of the manipulator. The numerical simulation results show that a better fitness value can be obtained with the QLIPSO algorithm. The linearity error of the curve of the manipulator， optimized by the proposed method， is decreased by 98.06% comparing with that non-optimized. It indicates that the proposed method can effectively improve the motion performance of the manipulator. References | Related Articles | Metrics

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Vehicle Suspension System State Estimation Combining with Interacting Multiple Model Kalman Filter GU Liang， WANG Zhen-yu， WANG Zhen-feng 2018, 39 (11):  1642-1647.  DOI: 10.12068/j.issn.1005-3026.2018.11.024 Abstract ( 678 )   HTML   PDF (1198KB) ( 831 )   In order to estimate accurately the vehicle suspension state， an interactive multiple model adaptive Kalman filter(IMMKF)state observer was proposed. Firstly， a standard road excitation model and a quarter vehicle linear model were established. Secondly， by combining recursive least square algorithm with IMMKF theory， an IMMKF state observer was designed based on the augmented suspension model in various working conditions. Finally， the influence on the state estimation of the suspension system with the change of sprung mass under the ISO level C road input excitation was analyzed. The results of simulation and experiment on a quarter of vehicle test rig showed that compared with the tradition Kalman filter(KF)state observer， the estimation accuracy of the proposed IMMKF state observer could be improved beyond 20% with the change of sprung mass. References | Related Articles | Metrics

Resources & Civil Engineering

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Critical Velocity of Sand Inrush and Flow Characteristics of Water-Sand in Thick Unconsolidated Formations of Mine in Western China YANG Bin， YANG Tian-hong， XU Zeng-he， YANG Xin 2018, 39 (11):  1648-1653.  DOI: 10.12068/j.issn.1005-3026.2018.11.025 Abstract ( 688 )   HTML   PDF (981KB) ( 751 )   Taking the Yuheng mine in Northern Shaanxi as an example， aeolian-sand incipience experiment and water-sand inrush experiment were expansion by high-velocity seepage and entire visual equipment of water-sand two-phase flow. The experiment results indicated that， the loss of fine particles is the precondition of water-sand inrush and creates expansive space for the coarse particle migration. The process of water-sand inrush is a physical process， when the aeolian-sand size between 0.3~0.6mm， the energy transmits mainly in the form of particles collision.But it is different for the aeolian-sand size between 0.15~0.3mm， because the friction and squeeze are in the dominant role， that will lose less energy compared with collision. So the variation mass of aeolian-sand inrush is inversely proportional to the particle size. The critical velocity of aeolian-sand inrush is becoming higher with the increasing of axial stress. When the aeolian-sand begins to move， the seepage state is linear laminar flow and the critical velocity is 0.03~0.4cm/s for the aeolian-sand size d<0.6mm.The mass of sand inrush is proportional to the hydraulic gradient in unit time. It can be deduced from this result that water pressure of aquifer is the key factor， which greatly decisive the disaster degree of water-sand inrush. References | Related Articles | Metrics

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Acoustic Emission Characteristics of Different Areas in the Fracture Process of Perforated Granite GAO Xiang， LIU Shan-jun， HUANG Jian-wei 2018, 39 (11):  1653-1657.  DOI: 10.12068/j.issn.1005-3026.2018.11.026 Abstract ( 625 )   HTML   PDF (1469KB) ( 642 )   The monitoring area of acoustic emission(AE)probes was partitioned by means of the blocking effect of hole on AE propagation. Based on the multi-channel AE monitoring experiment on perforated granite specimen under biaxial loading， the AE characteristics of different areas of specimens in failure process and its relationship with the failure mode were studied. The results show that AE sensors monitoring area of the specimens can be divided into three kinds， the single monitoring zone， the joint monitoring zone， and the blind monitoring zone. There are two kinds of fracture forms， the "V" type and the penetration type. For the specimens with V-type fracture， the main ruptures occur in the single monitoring zone and the AE characteristics of each channel are significantly different. For the specimens with penetration type fracture， the main ruptures happe in the joint monitoring zone and the AE characteristics of each channel are similar. References | Related Articles | Metrics

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Electric Spark Ignition Delay Time of Dust Clouds BU Ya-jie， YUAN Chun-miao， HAO Jian-tao， LI Chang 2018, 39 (11):  1658-1662.  DOI: 10.12068/j.issn.1005-3026.2018.11.027 Abstract ( 684 )   HTML   PDF (546KB) ( 666 )   To investigate the electric spark ignition sensitivity of dust clouds， using titanium powders as a sample， a mathematical model was established based on the gas-particle phase energy conservation equation with spark energy release rate as source phase. The influence of spark energy， particle size， ambient oxygen concentration， ambient temperature and turbulence on the ignition delay of dust cloud was obtained. Results show that particle size has the greatest impact on ignition delay， smaller particle size results in shorter ignition delay. When the ambient temperature is 50~100K higher than the room temperature， the ignition delay time is significantly shortened. Turbulence accelerates the heat transfer rate between particles and shortens the ignition delay time. In addition， the spark energy and the ambient oxygen concentration have little effect on the ignition delay. The calculation is considered as supplement to experimental research as well as theoretical basis for the relevant dust explosion prevention. References | Related Articles | Metrics

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Experimental Study on the Influence of Nanofiber Membrane on the Performance of Filter Media GUO Ying-he， HE Wei-dong， LIU Jing-xian 2018, 39 (11):  1662-1666.  DOI: 10.12068/j.issn.1005-3026.2018.11.028 Abstract ( 705 )   HTML   PDF (1155KB) ( 847 )   The nano-polyester filter with “sandwich” structure was prepared by electrospinning method. The dynamic performance of the polyester filter with or without the nanofiber membrane was tested. The results indicate that at the beginning of fresh filter stage， the resistance of nano-polyester filter increase rapidly. As the process progresses， the resistance grows slowly and the time required to complete each cycle is longer than polyester filter， the dust stripping rate of nano-polyester filter is 96.9%. At the aged stage， nano-polyester filter resistance increases by 81.9Pa and polyester filter increases by 112.3Pa. At the stabilized stage， the dust stripping rate of nano-polyester is 99.89% with the resistance growth slowly and long-time filtration cycle. The performance of nano-polyester filter is obviously better than that of polyester filter. References | Related Articles | Metrics

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Characteristics of Heavy Metal and PAHs in PM2.5 During Winter Pollution in Qinhuangdao ZHOU Xiu-yan， LI Na， LIU Ming-hua， WANG Shen-bo 2018, 39 (11):  1667-1672.  DOI: 10.12068/j.issn.1005-3026.2018.11.029 Abstract ( 811 )   HTML   PDF (655KB) ( 712 )   In order to explore the pollution characteristics and influencing factors of PM2.5 in Qinhuangdao in recent years， the PM2.5 samples from urban and development zones of Qinhuangdao during heavy pollution in winter were collected and analyzed. The quantities of 6 heavy metal elements(Cu， Pb， Zn， Cr， Ni， Cd)and polycyclic aromatic hydrocarbons(PAHs)in urban samples were determined by plasma emission spectrometer and gas chromatography-mass spectrometry. The results show that the average daily mass concentration of PM2.5 in Qinhuangdao urban is 186μg/m3， and the average concentration in the development area is 118.88μg/m3. The sequence of concentrations of heavy metals in urban PM2.5 are Zn > Pb > Ni > Cr > Cu > Cd. Among them， Cd is strong to strong pollution， Pb is medium to strong pollution， and Zn is medium pollution， other elements such as Ni， Cu， Cr are basically pollution-free. The monomers of PAHs， such as Naphthalene(Nap)， phenanthrene(Phe)， fluoranthene(Fla)， pyrene(Pyr)， benzo(k)fluoranthene(BkF)and so on， are qualitatively detected in these samples of PM2.5. The daily concentration of PM2.5 is negatively correlated with wind speed and positively correlated with relative humidity. References | Related Articles | Metrics