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Information & Control

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H∞ Control of Networked Control Systems with TimeVarying Sampling Periods and Partially Known Packet Dropout Information LI Yuan， ZHANG Pengfei， ZHANG Qingling 2014, 35 (3):  305-308.  DOI: 10.12068/j.issn.1005-3026.2014.03.001 Abstract ( 553 )   HTML   PDF (396KB) ( 674 )   The H∞ control problem for networked control systems(NCSs) based on timevarying sampling periods was studied. Since the successive packetdropouts were driven by an independent finite Markov chain， the NCSs with the networkedinduced delays and packetdropouts were modeled as Markov jump systems by designing the state feedback controller. Aiming at the fact that the packet dropout information was hard to be obtained accurately， namely it did not need to know the transition probabilities completely， the sufficient condition for stochastic stability with H∞ norm bound γhkj was presented on the basis of Lyapunov method. The stabilizing controller was constructed in terms of linear matrix inequalities (LMIs). The results of the numerical examples demonstrated the H∞ performance better than the existing methods. References | Related Articles | Metrics

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Robust H∞Control for DiscreteTime Switched Singular Systems with NormBounded Uncertainties and TimeDelay YANG Dongmei， MENG Xinquan 2014, 35 (3):  309-313.  DOI: 10.12068/j.issn.1005-3026.2014.03.002 Abstract ( 681 )   HTML   PDF (330KB) ( 565 )   The problem of robust H∞control for a class of discretetime singular systems with normbounded uncertainties and delaydependent was investigated. Firstly， based on linear matrix inequality(LMI)， combined with complete theory， by means of the multiple Lyapunov function method， under the appropriate switching rules， a sufficient condition was proposed for the problem to be solvable with all admissible uncertainties state delay; then， based on this condition， a delaydependent sufficient condition was proposed by designing the corresponding subcontrollers， such that the closedloop system was guaranteed robust stable and had H∞performance. Numerical examples show that the method is effective. References | Related Articles | Metrics

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Ladle Furnace End Point Sulphur Content Prediction Model Based on Model Migration Method〓 LYU Wu， MAO Zhizhong， YUAN Ping， JIA Mingxing 2014, 35 (3):  314-317.  DOI: 10.12068/j.issn.1005-3026.2014.03.003 Abstract ( 592 )   HTML   PDF (471KB) ( 577 )   Because of the modeling problems of the ladle furnace (LF) desulfurization process that are nonlinear， intensive dynamic and characterized of multiple conditions， end point sulphur content prediction model was proposed based on local model migration algorithm， where a simplified principle model was first established to capture the main process behavior and fine corrected by local model migration method to compensate the remain prediction error caused by mechanism simplification process and condition changes. A new local model migration algorithm was developed to automatically rectify the process nonlinearity deviation. The new method works by integrating several local migration models that are established in several local regions of the input space. The presented predictor shows better performance with respect to existing intelligent predictors due to the full exploitation of first principles， which is validated by the practical data. References | Related Articles | Metrics

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Model and Algorithm for Network Design of the Fourth Party Logistics Based on Resilience LI Rui， HUANG Min， ZHANG Ruiyou， WANG Xingwei 2014, 35 (3):  318-322.  DOI: 10.12068/j.issn.1005-3026.2014.03.004 Abstract ( 663 )   HTML   PDF (469KB) ( 491 )   It is very important to design a secure and efficient logistics service network for the fourth party logistics (4PL). The 4PL resilient network design problem was studied， and a model of 4PL network design was established， which minimized the total costs objective to the resilience constraint. For the NP characteristics of the problem， a hybrid particle swarm optimization with iterative local search method was developed and the performance of the algorithm was tested by randomly generated examples. The experiments verify the validity of the model and indicate that the PSO_ILS outperforms the classic PSO and has robustness against the main parameters. References | Related Articles | Metrics

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TeachingLearning Based Optimization Algorithm with Crossover Operation GAO Liqun， OUYANG Haibin， KONG Xiangyong， LIU Hongzhi 2014, 35 (3):  323-327.  DOI: 10.12068/j.issn.1005-3026.2014.03.005 Abstract ( 768 )   HTML   PDF (338KB) ( 750 )   Since the teachinglearning based optimization (TLBO) algorithm was easily trapped into local optima in solving unconstrained numerical optimization problems， a teachinglearning based optimization algorithm with crossover operation was proposed. The crossover operation of differential evolution was incorporated into TLBO， this operation was effectively integrating teaching and learning stage and it was beneficial to enhance local search and balance exploitation and exploration. The numerical results show that the proposed algorithm is better than TLBO， ITLBO and other intelligent methods in terms of optimization precision， convergence speed and robustness， and the algorithm has good perspectives. References | Related Articles | Metrics

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An Improved Differential Evolution Algorithm for Large Scale Reliability Problems KONG Xiangyong， GAO Liqun， OUYANG Haibin， GE Yanfeng 2014, 35 (3):  328-332.  DOI: 10.12068/j.issn.1005-3026.2014.03.006 Abstract ( 657 )   HTML   PDF (357KB) ( 626 )   In order to overcome the limitations of differential evolution algorithm with typical mutation operators， an improved adaptive differential evolution algorithm was proposed with a new mutation operator with global acceleration. The global acceleration operator can balance the global search and local search， such that the algorithm has higher optimization efficiency. According to the difference vector and the population distribution， the value of mutation rate was selected to slow down the trend of search scope narrow to maintain high population diversity. The crossover rate was adaptively chosen from two intervals through learning and comparing to meet the needs of the evolutionary search and improve the versatility of the algorithm. The improved algorithm is applied to the largescale reliability problems and the experimental results show that the improved algorithm achieves better optimization performance in solving largescale reliability problems. References | Related Articles | Metrics

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Sound Source Localization Algorithm Based on Time Delay Estimation ZHANG Chuanyi， MI Changwei 2014, 35 (3):  333-336.  DOI: 10.12068/j.issn.1005-3026.2014.03.007 Abstract ( 790 )   HTML   PDF (750KB) ( 2115 )   In order to solve the problems that there would not appear obvious peak with the basic crosscorrelation (BCC) in the time delay estimation (TDE) and the noise and reverberation in the actual environment would minify the BCC function′s peak and even leads to fake peaks，an improved time delay estimation method based on the generalized crosscorrelation (GCC) was presented and combined with the microphone array structure， so the twostep sound source localization method was implemented. Simulation results indicated that the sound source′s location could be measured accurately with the new method in noised environment. The average errors in positioning distance and angle are all below 5%. The successful rate of positioning is above 80% with the direction angle between 30° and 150° and the distance from 11m to 23m. References | Related Articles | Metrics

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Sensor Data Complement Method Based on Collaborative Filtering LI Fei， ZHANG Bin， GAO Yan， ZHANG Xinlong 2014, 35 (3):  337-341.  DOI: 10.12068/j.issn.1005-3026.2014.03.008 Abstract ( 695 )   HTML   PDF (402KB) ( 585 )   Completing the lack data monitored by the sensors is a key problem of the information sensing process in the Internet of things. In order to solve this problem， a method was proposed， which can complete sensor data by using collaborative filtering. Considering that there are a lot of similarities among monitor data from sensors in the same area or from the one with different periods， properties of spacetime correlation between sensors were adopted in the proposed method. Different similarity evaluation was used to select similar sensors by classifying sensors with missing data in order to ensure the accuracy of the estimate. The results showed that using this method to estimate the missing data was better than other methods when there are large changes in the environment. References | Related Articles | Metrics

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RDF Fuzzy Querying with Relative Quantifiers WANG Hairong， MA Zongmin 2014, 35 (3):  342-346.  DOI: 10.12068/j.issn.1005-3026.2014.03.009 Abstract ( 689 )   HTML   PDF (563KB) ( 602 )   In order to deal with the fuzzy queries of RDF with relative quantifiers， an approach of querying RDF with relative quantifiers was proposed， which can also support grouping mechanism. A linguistic hierarchy table reflecting various accuracies of fuzzy constraints was first constructed. An extended SPARQL syntax was hereby proposed by introducing fuzzy conditions in FILTER clause and calling GROUP BY and HAVING clauses to accomplish grouping operations over specific attributes. Two typical cases of fuzzy RDF querying with relative quantifiers were analyzed. On the basis， how to translate fuzzy SPARQL queries into classic SPARQL queries was investigated so that the existing SPARQL implementations can handle the fuzzy RDF querying with relative quantifiers. Finally， an experimental system is developed and the experimental results show the feasibility of the proposed approach. References | Related Articles | Metrics

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A Multiagent Flocking Oriented Obstacle Avoidance Algorithm ZHAO Hai， LIU Qian， SHAO Shiliang， LI Dazhou 2014, 35 (3):  347-350.  DOI: 10.12068/j.issn.1005-3026.2014.03.010 Abstract ( 696 )   HTML   PDF (464KB) ( 852 )   The problem of obstacle avoidance is important in multiagent flocking. Each agent should avoid obstacles safely， and then moves toward the target. Based on the existing artificial potential field flocking algorithm， an improved algorithm with obstacle avoidance capability was presented. In this algorithm， the obstacle was equivalent to a virtual agent for obstacle avoidance. Obstacle avoidance were not taken immediately when the agent perceived obstacles， but take the speed direction of the agent and the target point into consideration. According to different speed directions and position of the target， different obstacle avoidance measures will be taken. Through theoretical analysis and experimental verification， obstacles could be avoided efficiently based on the proposed algorithm， which can make the flocking faster. References | Related Articles | Metrics

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A Memory Management Approach Based on Page Coloring for Multicore Systems ZHANG Yi， GUAN Nan， WANG Yi 2014, 35 (3):  351-355.  DOI: 10.12068/j.issn.1005-3026.2014.03.011 Abstract ( 635 )   HTML   PDF (531KB) ( 794 )   Most multicore platforms currently adopt shared cache among the processor cores. Due to the problem of cache contention， it is extremely difficult to predict the worstcase execution time of the computation tasks running on different cores. A pagecoloring technique was proposed to avoid cache contention in memory access for multicore platforms. The advantage is that the worst case execution time of tasks running on individual core can be estimated separately using the existing WCET analysis methods for uniprocessor systems. A memory management system was designed based on the Linux to support page coloring mechanism， which is evaluated using the standard benchmarks. Experimental results shown that the execution time for different processor cores becomes deterministic when it is executed on the same platform running in the Linux supported with the management system. References | Related Articles | Metrics

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Hemodynamic Characteristics Analysis of Carotid Artery Bifurcation Based on CT Images ZHANG Yaonan， LI Yan， KANG Yan 2014, 35 (3):  356-360.  DOI: 10.12068/j.issn.1005-3026.2014.03.012 Abstract ( 692 )   HTML   PDF (1846KB) ( 961 )   The geometric model of a carotid artery bifurcation was constructed from the CT images of a real patient. Using this model， the velocity and pressure distribution of the carotid arteries were simulated by a finite element software ANSYS. Further analysis was done on the hemodynamic characteristics of the carotid artery bifurcation， such as the wall shear stress distribution at different time points， the blood velocity field at different time points， and the characteristics of turbulence. Finally the blood resistance of carotid arteries was analyzed. The results turned out that the wall shear stress is almost the lowest at the sinus， the turbulence occurs nearby the sinus. There is a high pulse for blood resistance at the beginning of systole period. These findings could be useful for relevant research of cardiovascular diseases. References | Related Articles | Metrics

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Design and Development of Huge Network Management Training Platform Based on Olive LIN Haizhuo， WANG Jilong， ZHANG Chengliang 2014, 35 (3):  361-365.  DOI: 10.12068/j.issn.1005-3026.2014.03.013 Abstract ( 589 )   HTML   PDF (1329KB) ( 534 )   Since all the network experiments are forbidden in the real network environment， how to train a qualified network administrator in the real network environment is a tough issue. A network management training platform was designed and implemented， which was capable of providing diversified experiments scenes. The platform proposed could be used to train the necessary skills for network administration， such as large networks implementation， network fault detection and recovery， network topology discovery， network attack and defense. Both the experiment of routing oscillation caused by human error in configuration and the experiment of maninthemiddle attack of neighbor discovery for IPv6 proved that the platform was capable of serving as a test bed to provide a research environment for network administrators. References | Related Articles | Metrics

Materials & Metallurgy

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Characterization of the Microtwinning of Mn3O4 in La1xSrxMnO3 Compounds SUN Benzhe， QI Yang 2014, 35 (3):  366-368.  DOI: 10.12068/j.issn.1005-3026.2014.03.014 Abstract ( 504 )   HTML   PDF (1472KB) ( 543 )   La1xSrxMnO3 (LSMO) manganite has been widely focused on due to its significant colossal magnetoresistance (CMR) effect， but a trace of impurity Mn3O4 suppresses the CMR effect. The microtwinning in Mn3O4 phase was characterized and its formation mechanism was analyzed systematically by means of transmission electron microscopy and the relative analytical methods. It was found that twin plane is defined as (112) and a small amount of Sr atoms are observed near the twin plane in Mn3O4 with anatase structure.Based on the relationships between the probability of microtwinning and the number of Sr atoms， it can be verified that the formation of microtwinning may be attributed to the decrease in the formation energy of twin boundary induced by the introduction of Sr atoms， which contributes to deduce the general rule on the structural evolution from anatase to perovskite. References | Related Articles | Metrics

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Investigations on the Temperature for Completion of Austenite Transformation During the Initial Solidification Process of Microalloy Steels LIU Jiang， WEN Guanghua， TANG Ping， LI Yunfeng 2014, 35 (3):  370-374.  DOI: 10.12068/j.issn.1005-3026.2014.03.015 Abstract ( 598 )   HTML   PDF (875KB) ( 579 )   Coarse austenite grain formed in the initial solidification process is an important factor to affect the transverse cracking of medium carbon microalloyed steels.The initial solidification process of P510L steels were observed by the confocal laser scanning microscope in order to inspect the formation of δ and γ phases and the peritectic reaction，and explore the temperature for the completion of γ transformation. The results showed that:1) With the cooling rate of 25℃/s， the cooling mode of P510L steel was that δferrite precipitated from the liquid phase first， then the peritectic reaction (L+δ→γ)occured between the δferrite phase and the liquid phase， then they entered to the threephase coexistence region. With the liquid phase disappeared， the remain δ phase transformed into γ phase by the solid state diffusion;2) In the initial solidification process， parts of the austenite grains annexed and grew up first， then the remain δferrite transformed into austenite with the allotropic heterogeneous， and the fully austenite region achieved at last; 3) A more accurate method about determining the temperature for the completion of γ transformation was sought by insitu dynamic observation， and the accuracy of a model for predicting the austenite grain size was thus improved. References | Related Articles | Metrics

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Effects of OverAging Temperatures on Microstructure and Mechanical Properties of Low Cost Cold Rolled Dual Phase Steels LIU Jiyuan， LUO Zongan， SHI Minghao， ZHU Fuxian 2014, 35 (3):  375-378.  DOI: 10.12068/j.issn.1005-3026.2014.03.016 Abstract ( 691 )   HTML   PDF (724KB) ( 708 )   A high strength and ductility dual phase steel was developed from the traditional steel via establishing reasonable processing parameter windows， which transferred from low to high additional values. The continuous annealing specimen was prepared from CMn steels by hot and cold rolling. The microstructure contained ferrite and martensite was obtained by the intercritical anneal， controlled cooling and the subsequent different overaging procedures. The bainite transformation was avoided when the overaging temperature was lower than 320℃. The volume fraction of the martensite increased with the decrease of temperatures. The tensile strength was proportional to the volume fraction of the martensites， whereas the yield strength and elongation performanced an inverse relationship. The strengthductility balance was 182546 MPa% in the 320℃ overaging procedure as a better mechanical property. References | Related Articles | Metrics

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Effects of the Heavy Reduction Rolling on the Microstructure and Edge Crack of Casted Magnesium Alloys DING Yunpeng， LE Qichi， ZHANG Zhiqiang， CUI Jianzhong 2014, 35 (3):  379-383.  DOI: 10.12068/j.issn.1005-3026.2014.03.017 Abstract ( 677 )   HTML   PDF (1227KB) ( 718 )   The effects of the reduction per pass and the number of rolling passes on edge cracks and microstructure were investigated when the magnesium AZ31B sheets were processed by hot rolling with large reduction from slabs. The sheets were subjected to twopass or fourpass rolling at 350℃. The specimens were examined by optical microscopy， edge crack statistic and Xray diffraction. The results indicated that edge cracks appeared when the reduction rates reached 37%， and the edge crack depth increased with the increase of reduction rate. The twins also increased with the increase of the reduction rate. When total reduction rate reached 54%， most of part of the microstructure was completed.When the reduction rate increased further， shear bands appeared. For the rolling with 82% total reduction， when the rolling pass increased， the level of edge cracks decreased to some extent. Meanwhile， the basal texture changes from two basal poles to only one. References | Related Articles | Metrics

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Calculation Analysis of Zinc Dissolution Behaviors of the SlagIron in Blast Furnaces JIAO Kexin， ZHANG Jianliang， ZUO Haibin， LIU Zhengjian 2014, 35 (3):  383-386.  DOI: 10.12068/j.issn.1005-3026.2014.03.018 Abstract ( 787 )   HTML   PDF (441KB) ( 905 )   Based on the material balance and zinc balance calculation， through the analysis of zinc behaviors in lower part of blast furnace， a calculation model for zinc solution behaviors among the slag and the hot metal was established.Zn index at BF bosh was proposed to represent the degree of circulating enrichment of zinc. The practical data of a steelwork was used for calculation， and the index of the zinc content of the coal gas in bosh of the blast furnace was 568. Zinc was in the saturation state in both slags and hot metals in the furnace， and the content of it was 316 times and 10 times as much as that in the final room temperature condition for the slag and hot metal respectively. The accumulation mechanism in blast furnace bottom brick and the erosion mechanism of zinc on tuyere were also analyzed， offering references for alleviating destructive effects of zinc on the blast furnace. References | Related Articles | Metrics

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Preparation and Properties of UV Curable InorganicOrganic Composite Coatings LIU Fengguo， DAN Baohua， XUE Xiangxin， YANG He 2014, 35 (3):  388-391.  DOI: 10.12068/j.issn.1005-3026.2014.03.019 Abstract ( 627 )   HTML   PDF (404KB) ( 598 )   UV curable inorganicorganic composite coatings containing SiO2 nanoparticles based on the epoxy acrylate (EA) were prepared by the blending method. The structure， thermal stability and physical properties of the composite coatings were investigated. The results indicated that Si—O—Si crosslinked network structures are generated in the coatings due to the incorporation of SiO2 nanoparticles， which contributed to improve the thermal stability of the coatings. The composite coating with 5% mass fraction of SiO2 nanoparticles exhibits the most excellent thermal stability. With the increase of the content of SiO2， the gloss of the coatings decreases. Moreover， the reasonable amounts of SiO2 addition can improve the hardness of the coatings. When the mass fraction of SiO2 is 3%~5%， the composite coating exhibits 3H pencil hardness. References | Related Articles | Metrics

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Separation and Recovery of Copper from Bioleaching Solution of LowGrade Carrollite LI Haijun， YANG Hongying， CHEN Guobao， LUO Wenjie 2014, 35 (3):  391-395.  DOI: 10.12068/j.issn.1005-3026.2014.03.020 Abstract ( 609 )   HTML   PDF (560KB) ( 907 )   Biological leaching solution of lowgrade carrollite often contains a high concentrations of iron， a low concentrations of cobalt and a amount of copper when using the biological oxidation method. So the selective separation of copper was carried out before the recovery of cobalt to avoid the loss of cobalt.LIX984N as an extractant was used to selectively separated and extracted copper from the lowgrade carrollite biological leaching solution. The results showed that，when the volume fraction of LIX984N is 25%， ambient temperature 35℃， O/A 1∶1， mixing time 5 min and equilibrium pH 125， the extraction rate of copper is 994%.Under the same condition， the extraction rates of the iron of entrainment and the cobalt was only 403% and 0849% respectively. Loaded organic phase was washed by pure water under O/A 1∶1， the extraction rates of the cobalt and iron of entrainment decreased to 0008% and 0766% respectively. After washing， loaded organic phase was stripped using sulfuric acid solution with concentration of 200g/L.When O/A was 1∶1， after two countercurrent stripping，the copper stripping rate was 9813%. References | Related Articles | Metrics

Mechanical Engineering

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Nonlinear Characteristics Analysis of Gear Pairs with the Impact of Rotational Speed and Torque ZHANG Yimin， LU Jinchang， HU Peng 2014, 35 (3):  397-401.  DOI: 10.12068/j.issn.1005-3026.2014.03.021 Abstract ( 794 )   HTML   PDF (837KB) ( 948 )   A nonlinear twodegreeoffreedom dynamics model for a spur gear pair system is developed by considering the timevarying stiffness，mesh damping，backlash and transmission error. The differential equations were solved by the fourthorder variable step size RungeKutta algorithm. The statistics of the proportion of tooth contact states in the iterative process were acquired，and the impact of the rotational speed and torque on dynamic transmission error was studied. It shown that the tooth mesh condition changes with the increase of rotational speed，which explains the cycle and chaos response of the dynamic transmission error and the error amplitude jump phenomena. With the increase of torque，jumping phenomenon of the rotational speed increased，the changes of amplitude also increased，but the tooth impact reduced. References | Related Articles | Metrics

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Response of Nonlinear BendingTorsional Coupling Vibration of the Combustion Engine Crankshaft System LIANG Mingxuan， YUAN Huiqun， ZHAO Tianyu， CAI Yingying 2014, 35 (3):  402-405.  DOI: 10.12068/j.issn.1005-3026.2014.03.022 Abstract ( 580 )   HTML   PDF (995KB) ( 579 )   The bendingtorsional coupling dynamic model of the crankshaft system in combustion engine was presented by considering varied inertia， mass eccentricity and nonlinear friction damping force. Numerical integration methods were adopted to analyze the effects of the mass eccentricity and rotate speed on the dynamic performance， and the characteristics of amplitude frequency responses were obtained based on the harmonic balance method. It is shown that the harmonic balance method coincides well with the numerical method. The damping between the cylinder and piston can produce significant inhibition of system response amplitude. The motion stability can be effectively improved by reducing the eccentric of crankshaft system. References | Related Articles | Metrics

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Research on Dynamic Reliability Sensitivity of the Indexable Cutting Tool WANG Xingang， LYU Chunmei， PANG Xu， WANG Xueling 2014, 35 (3):  406-410.  DOI: 10.12068/j.issn.1005-3026.2014.03.023 Abstract ( 714 )   HTML   PDF (582KB) ( 511 )   In the interrupted cutting process， the main failure mode of the indexable cutting tool is endurance failure. The selection of design parameters of the cutting tool is important， which has direct effect on its reliability. A mathematical model of the dynamic reliability for hard alloy cutter was successfully built based on the stressstrength interference model， and the change rule of its reliability in the machining period was also obtained. Combining with sensitivity analysis method， the computational formulas of the dynamic reliability sensitivity and the change curves of design parameters were derived. The study shows that due to the different sensitive degree of design parameters to the cutting reliability， the selection of sensitive parameters should be controlled so as to improve reliability of the cutting tool and the accuracy of the processed accessory. Meanwhile， the proposed method provides a theoretical basis for enhancing the reliability of the tool system and the whole machine tool. References | Related Articles | Metrics

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Modal Analysis of the Rotor System of TurboMolecular Pump Based on FiniteElement Method WANG Xiaodong， SUN Yan， FANG Liwu， LI Xiaoyong 2014, 35 (3):  411-413.  DOI: 10.12068/j.issn.1005-3026.2014.03.024 Abstract ( 696 )   HTML   PDF (988KB) ( 711 )   The geometric model of FB1500 turbomolecular pump (TMP) rotor system was established based on the construction， parameters and material of the rotor， the bearing support style and mass distribution of rotor. The critical speeds and the vibration modes were obtained by the modal analysis of TMP rotor system based on the commercial finiteelement code ANSYS. The modal analysis results show that the TMP is operated between the speed of 5 and 6 order natural frequency，but it is not fully satisfy the design theory of the flexible drive system to avoid the sympathetic vibration during TMP operation.The natural frequency of TMP rotor system can be increased with the moment of inertia increasing， and a structure improvement of TMP rotor system was proposed to increase the TMP operating reliability. References | Related Articles | Metrics

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Experimental Study on the Performance of Multidecked Elastic Support Protuberant Foil Gas Bearing LAI Tianwei， ZHENG Yueqing， CHEN Shuangtao， HOU Yu 2014, 35 (3):  415-418.  DOI: 10.12068/j.issn.1005-3026.2014.03.025 Abstract ( 686 )   HTML   PDF (970KB) ( 637 )   Based on the single deck protuberant foil gas bearing，a new type of foil bearing composed of multidecked structure was proposed. The relative position of the protuberant of different decks arranged to produce variable stiffness and damping effects.This new configuration possesses controllable stiffness in axial and circumferential direction，as well as the additional coulomb damping between the stacked layers， could improve the bearing stability.In the experiment， the maximal running speed of the 25mm diameter rotor in the turboexpander reached 99044 r/min. In the whole speed up and down processes， the amplitude of subsynchronous whirl is small which verifies the suppression effect of the new configuration， therefore， this new foil bearing can be applied in high speed turbomachinery. References | Related Articles | Metrics

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EEG Feature Extraction Based on Constrained ICA HUANG Lu， WANG Hong 2014, 35 (3):  419-423.  DOI: 10.12068/j.issn.1005-3026.2014.03.026 Abstract ( 598 )   HTML   PDF (409KB) ( 1009 )   Considering the current timeconsuming feature extraction of the braincomputer interface， a feature extraction method based on constrained ICA was proposed for P300BCI. The temporal P300 character of every subject was studied using the EEG image， and then， reference signals were built according to the temporal P300 character. Using the reference signals combined with ICA， the most correlative independent components were extracted based on 64channel EEG. According to the extracted independent components， 3dimensional feature vectors were built and put into the linear classifier at last. Two public datasets of BCI Competition II and III were used to verify the method. The results show that the recognition accuracy can be improved to 671% only with three times average， and to 952% with fifteen times average. The computation time is also shorter than other methods in the same experimental conditions. References | Related Articles | Metrics

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Biomechanical Analysis of Mandible Based on ABAQUS CHEN Yadong， MA Guoqiang， SHANG Dehao， WANG Wanshan 2014, 35 (3):  423-428.  DOI: 10.12068/j.issn.1005-3026.2014.03.027 Abstract ( 917 )   HTML   PDF (825KB) ( 1103 )   In order to improve the individual matching of free fibula flap for mandible defect reconstruction， a custommade titanium plate design and manufacture were presented. The visualization and CAD were adopted to design the repair model with biomimetic shape by CT data. A finite element model of the mandible was created. The stress of the mandible before and after repair was compared with each other. Rapid prototyping was employed to build the resin mold， which can save the surgery time and improve the success rate. The mandible finite element analysis results show that the mandible stress concentration area was broadly distributed in mandible ankle protrusion area， mandibular angle，and the mandible repair. With increase of the loading force， stress increased significantly， especially in mandible ankle protrusion area and the mandible repair. The maximum stress appeared at the junction of the mandible and fibula. The high stress generalization of the repaired mandible was checked. Areas of stress concentration decreased significantly. References | Related Articles | Metrics

Resources & Civil Engineering

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Contrastive Analysis of Microseismic Events for Immediate Rockburst in Deep Tunnels with Different Excavation Methods YU Yang， FENG Xiating， CHEN Tianyu， CHEN Dongfang 2014, 35 (3):  429-432.  DOI: 10.12068/j.issn.1005-3026.2014.03.028 Abstract ( 544 )   HTML   PDF (652KB) ( 701 )   Based on continuous and realtime microseismic monitoring for construction process of diversion tunnels and drain tunnels in a hydropower station， the microseismic information of tunnels excavated by drillandblast method and tunnel boring machine (TBM) were compared and analyzed. The results show that duirng the preparation and germination of immediate rockbursts in deepburied tunnel excavation， the distribution of microseismic events and energy release gradually convert from discrete to relatively concentrative mode in spatial domain， and the number of microseismic events increases obviously. Accumulated released energy of microseismic events and average released energy of plastic volume increase. Energy release of tunnels excavated by TBM is bigger than that by drillandblast method. Before the occurrence of strong rockbursts，there are a lot of mild and moderate rock bursts in the excavation by TBM， which is not found in drillandblast method excavation. References | Related Articles | Metrics

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Experiment of Characteristics of Acoustic Emission During Granite Fracture Based on Moment Tensor Analysis XU Shida， LI Yuanhui， LIU Jianpo， HUANG Wenbai 2014, 35 (3):  433-436.  DOI: 10.12068/j.issn.1005-3026.2014.03.029 Abstract ( 697 )   HTML   PDF (930KB) ( 757 )   Based on the acoustic emission (AE) location technology and moment tensor analysis method， the experiment study of fracture mechanism and time and space distribution characteristics of the cracks during fracture process of rock specimens under uniaxial compression was conducted. The acoustic emission events with different fracture mechanisms can be used to identify the forms of the cracks directly with the help of CAD software. The results show that shear failure was more than other failure types in granite sample under uniaxial loading. However， the form of microcrack that may have no fixed proportion is determined by its mechanics environment. It is a phenomenon that， the brittle fracture of granite does not agree with the Griffith strength criterion where the fracture is considered to be caused by tensile in brittle materials， thus clarifying the limitations of the Griffith strength criterion. AE generated by different sample types fracture， which is independent of the stress level， has similar trend in the increasing stress during uniaxial loading of granite. References | Related Articles | Metrics

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Data Amendment of Abnormal Point Cloud of Goaf by Laser Scan in Deep Complex Environment XIONG Lixin， LUO Zhouquan， LUO Zhenyan， XIE Chengyu 2014, 35 (3):  438-443.  DOI: 10.12068/j.issn.1005-3026.2014.03.030 Abstract ( 583 )   HTML   PDF (1007KB) ( 788 )   The topology relationship of laser trace lines was analyzed. The abnormal points were divided into two categories:dead points and noise points. The environmental factors that affect the dead point error in laser detection were analyzed. The 3D point cloud data were obtained as XYZ format data files， and the data amendment algorithms for dead points were proposed based on 4point interpolation. Moreover， the noise filtering algorithms for the minimal angle and stringheight ratio of noise points based on G2continuity were proposed. The validation shows that the volume， the exposed roof area and roof height are consistent with the reality after reconstruction. For example，the volume revised about 20~70m3， and the height of roof increased about 1~2m. The algorithms is simple logically and less timeconsuming， thereby providing a new method for dealing with goaf point cloud data. References | Related Articles | Metrics

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Zircon UPb Dating and Petrogenesis of the Rhyolitic Porphyroclastic Lava in Chaihe Area， Daxinganling Mountains SI Qiuliang， CUI Tianri， WANG Ende， MEN Yekai 2014, 35 (3):  443-445.  DOI: 10.12068/j.issn.1005-3026.2014.03.031 Abstract ( 645 )   HTML   PDF (596KB) ( 646 )   In order to study the formation age and petrogenesis of the rhyolitic porphyroclastic lava in Chaihe area， Daxinganling mountains， ziron UPb isotopic dating and geochemical analysis were used. LAICPMS zircon UPb dating results show that Chaihe rhyolitic porphyroclastic lava formed in early cretaceous from 135 to 138Ma. The geochemical study show that characteristics of the rhyolitic porphyroclastic lava have high silicon and alkalis， poor calcium and magnesium. The total REE abundances ranged from 1501×10-6~1915×10-6， highly fractionated LREE from HREE［m(La)/m(Yb)N=118~1445］and negative Eu anomalies (δEu=059~075). The trace elements are characterized evidently by enrichment of Rb，Ba，K， strong depletion of Nb， P， Ti. The geochemical characteristics show similarity with the Itype granite. The porphyroclastic lava’s original magma is chiefly derived from partial melting of crust. References | Related Articles | Metrics

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Study on Excess Sludge Disintegration by Ultrasonic Treatment YOU Meiyan， LI Xianjin， WANG Liwei， ZHU Tong 2014, 35 (3):  447-451.  DOI: 10.12068/j.issn.1005-3026.2014.03.032 Abstract ( 616 )   HTML   PDF (502KB) ( 584 )   The influences of ultrasonic time， ultrasonic frequency， ultrasonic power， ultrasonic pulse ratio， along with the interaction between ultrasonic time and frequency， time and power， power and frequency factors on the ultrasonic disintegration effect of excess sludge were studied by orthogonal test of mixedlevel interaction.The results show that the optimal combination parameters of the ultrasonic disintegration sludge list as the ultrasonic time of 7 minutes， the ultrasonic frequency of 20 kHz， the ultrasonic power of 600 W， the ultrasonic pulse ratio of 3∶1， and the interaction effects among the three factors of the four are not obvious. It is found that appropriately improving the sludge concentration would gain a better disintegration effect after studying the seven different solid concentration liquor suspended sludge disintegrated by ultrasonic. The time curves of ultrasonic disintegration sludge indicate that the disintegrating rate of each index increases slowly when the sludge is disintegrated after 40 minutes， and the highest energy utilization of ultrasonic disintegration sludge appears during 15 to 20 minutes. References | Related Articles | Metrics

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Effects of InSitu Mining of Oil Shale on Rock Mass Structure JIANG Xue， LIANG Xiujuan， WEI Runchu， XIAO Changlai 2014, 35 (3):  452-456.  DOI: 10.12068/j.issn.1005-3026.2014.03.033 Abstract ( 666 )   HTML   PDF (840KB) ( 508 )   Physical and mechanical parameters of the oil shale and its wall rock from Fuyu County in Jilin Province were measured， on the basis of which， unit weight， elasticitymodulus， Poisson′s ratio， internal frictional angle， cohesion and other parameters were obtained. And the SIGMA/W module was used to calculate elasticplastic finite element model， thus，the stress，stain and displacement of any point within insitu mining area were gained. The results show that the maximum subsidence displacement is 105m， which is located at the center of mining.Meanwhile， according to these information， the stress distribution of rock mass is analyzed. Tension zone is consistent with larger shear stress extreme distribution area， both are located in shale which is the overlying strata of oil shale， thus the failure process of rock mass is determined. First， rock mass is stretched， producing a large number of cracks， and then occurs sliding along the crosssection where the shear stress extreme. References | Related Articles | Metrics