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15 July 2014, Volume 35 Issue 7 Previous Issue    Next Issue
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Information & Control

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Modeling Method for Tree in the Rainfall Area YU Shun， ZHANG Tie 2014, 35 (7):  913-916.  DOI: 10.12068/j.issn.1005-3026.2014.07.001 Abstract ( 618 )   HTML   PDF (495KB) ( 644 )   It is difficult to find an efficient tree modeling method because of its own complexity and wind， rain acting on tree. A tree modeling method was constructed which could indicate the intrinsic structural characteristic， complex forms and the effects by the wind，rain， snow and other natural phenomena. Firstly， static model was constructed， based on which the dynamic model was established in which the effects on the tree by the wind， rain， snow and other natural phenomena were considered. The force was calculated by the momentum theorem based on the dynamic model in the wind. And then the value of rupture limit was compared to the Young’s modulus in order to determine the situation of fracture or sway. Thus， the tree dynamic model could be improved in the nature environment. During the modeling process， it was found that dynamic model with this method can reduce time decay and keep the modeling fidelity. References | Related Articles | Metrics

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Strain Estimation Method Based on 2D Companding and Optical Flow ZHANG Yaonan， LI Hongliang， ZHENG Hairong， KANG Yan 2014, 35 (7):  917-921.  DOI: 10.12068/j.issn.1005-3026.2014.07.002 Abstract ( 607 )   HTML   PDF (754KB) ( 787 )   In order to get accurate strain estimation in ultrasound elastography， it is important to eliminate the decorrelation caused by the lateral displacement of the longitudinal compression. A new strain estimation method was proposed by combining the twodimensional companding and optical flow method. First， the twodimensional Hibert transformation was used to convert the original ultrasound RF signals to the analytical signals by the envelop detection. Then， the block matching method was used to get the motion vectors of 16 subblocks. Based on the motion vectors， a linear regression method was used to estimate the parameters of the twodimensional companding. After the twodimensional companding， the optical flow method was employed to estimate the subpixel motion. Experimental results showed that the overall strain estimation accuracy and robustness could be enhanced by the proposed twodimensional companding methods. The longitudinal displacement and longitudinal strain obtained by the proposed method were basically consistent with those obtained by the finite element simulation， which proved the correctness of the new method. Related Articles | Metrics

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RangeFree Localization Algorithm Based on Estimated Distances MENG Yinghui， WEN Yingyou， CHEN Jian， ZHAO Hong 2014, 35 (7):  921-925.  DOI: 10.12068/j.issn.1005-3026.2014.07.003 Abstract ( 591 )   HTML   PDF (611KB) ( 692 )   Due to the large localization error of rangefree localization algorithms， a rangefree localization algorithm based on estimated distances was proposed. Firstly， a linear function was designed by analyzing the relation between the distance of two neighbor nodes and the intersection area of them. The output was a distance parameter which could represent the distance of neighbor nodes. Then， estimated distances between nodes were calculated based on distances of anchor nodes. Finally， the estimated positions of nonanchor nodes were calculated based on estimated distances. Simulation results showed that the localization error of the proposed algorithm is smaller than that of the current rangefree algorithms in both regular and irregular areas. References | Related Articles | Metrics

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ECG Compression Algorithm Based on Empirical Mode Decomposition YANG Dan， QIN Mengzhi， XU Bin， WANG Xu 2014, 35 (7):  926-930.  DOI: 10.12068/j.issn.1005-3026.2014.07.004 Abstract ( 725 )   HTML   PDF (743KB) ( 1226 )   A compression algorithm based on empirical mode decomposition(EMD)was described in order to investigate the performance of EMD in biomedical signals， and especially in the case of electrocardiogram(ECG). The proposed algorithm was computationally simple to treat nonstationary and nonlinear data without pre or postprocessing. In order to evaluate the performance of the proposed compression algorithm， MITBIH arrhythmia database was applied， and some important parameters were obtained， such as the compress ratio(CR)， percent root mean square difference(PRD)， percent root mean square difference normalized(PRDN)， root mean square(RMS)， signal to noise ratio(SNR)， and quality score(QS)values. Experimental results indicated that the proposed algorithm has a better compress ratio and fidelity， which proved the feasibility of the proposed algorithm. References | Related Articles | Metrics

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Analysis of Tunable Refractive Index Characteristics of the Magnetic Fluid WU Di， ZHAO Yong， LYU Riqing， YING Yu 2014, 35 (7):  931-934.  DOI: 10.12068/j.issn.1005-3026.2014.07.005 Abstract ( 1119 )   HTML   PDF (499KB) ( 1259 )   Temperature and magnetic field are the two factors which will affect the magnetic fluid refractive index through theoretical analysis. A method with independent sensing probes based on the principle of Fresnel reflection was presented. Experimental measurements were carried out to investigate the relation between the magnetic field intensity and temperature dependent refractive index of the magnetic fluid. The results showed that， for a given concentration of the magnetic fluid， the effect of temperature on nMF was relatively insignificant with a sensitivity of -802×10-5℃-1 under zero magnetic field intensity. When there was an external magnetic field(parallel to the propagation direction of light)， the nMF would increase with the increase of the magnetic field intensity at constant temperature. The repeatable performance of this device was also proved to be perfect. The tunable refractive index characteristics of magnetic fluid could be used as the theoretical basement for filling into the photonic crystal fiber(grating)to achieve a magnetic field and temperature sensing. References | Related Articles | Metrics

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An Dynamic Restart Strategy for Solving SAT Problem GUO Ying， ZHANG Changsheng， ZHANG Bin 2014, 35 (7):  935-938.  DOI: 10.12068/j.issn.1005-3026.2014.07.006 Abstract ( 751 )   HTML   PDF (409KB) ( 813 )   In order to reduce the computational costs in conflictdriven clause learning solvers， an improved adaptive heuristic restart strategy named 2WSAT was proposed， which was based on two questions including“when to restart”and“where to restart”. In this strategy， the conflict decision levels and variable’s restart times were taken as important solving state parameters， so that overall performance could be improved by escaping from wrong search branches and choosing better decision variables. Comparative experiments were conducted among 2WSAT and two modern solvers， using the practical application benchmarks. The results showed that 2WSAT has higher scores in many key indicators such as solving speed， memory usage， conflicts number， propagation number etc. References | Related Articles | Metrics

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Modified Scheduling Algorithm for Cloud Workflow Based on QoS WANG Yan， WANG Jinkuan， WANG Cuirong， HAN Yinghua 2014, 35 (7):  939-943.  DOI: 10.12068/j.issn.1005-3026.2014.07.007 Abstract ( 772 )   HTML   PDF (466KB) ( 1017 )   According to the users’ requirements of QoStime and execution costs， the scheduling strategies for workflow were modified by combining the cloud computing and workflow. For the problem that workflow efficiency of instanceintensive cloud workflows was not high in a cloud environment， the cloud workflow scheduling model and the modified scheduling algorithm for cloud workflow were proposed based on QoS. DAG was used in the algorithm， and resource strategy was modified to meet the latest execution time under the premise of minimizing the entire workflow execution costs. The experimental results showed that the efficiency effectively improved and the cost of using resource was reduced with the proposed algorithm. References | Related Articles | Metrics

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FilterBased Probabilistic Skyline Query Processing Algorithm in Wireless Sensor Network XIN Junchang， SHI Lingxu， WANG Pei， WANG Zhiqiong 2014, 35 (7):  944-948.  DOI: 10.12068/j.issn.1005-3026.2014.07.008 Abstract ( 620 )   HTML   PDF (444KB) ( 529 )   Due to the inherent uncertainty of sensing data， the processing and optimization techniques for probabilistic Skyline(PS)in wireless sensor networks(WSNs)were investigated. It has been proved that PS was not decomposable after analyzing its properties， so innetwork aggregation techniques could not be used directly to improve the performance. Therefore， a filterbased probabilistic Skyline query processing algorithm in WSNs(FPSP)was proposed to evaluate the PS query in WSNs. The sensing data were divided into candidate data(CD)， relevant data(RD)， and irrelevant data(ID)by the proposed FPSP. The ID in each sensor node could be filtered directly so as to reduce data transmission cost， since PS result could be correctly obtained only according to CD and RD on the base station. The experimental results showed that most of the unnecessary data can be effectively filtered and the lifetime of WSNs can be greatly prolonged by the proposed FPSP algorithm. References | Related Articles | Metrics

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Adaptive Kalman Asynchronous IC Multiuser Detector for Fading Channel GAO Weiting， LI Hui 2014, 35 (7):  949-953.  DOI: 10.12068/j.issn.1005-3026.2014.07.009 Abstract ( 519 )   HTML   PDF (1014KB) ( 683 )   In order to solve the problem of multiuser detection(MUD)judgment error diffusion of single successive interference cancellation(SIC)and parallel interference cancellation(PIC)algorithm，the interference cancellation algorithm of direct sequence spread spectrum code division multiple access(DSCDMA)system was studied under condition of strong multiple access interference(MAI). A KAIC cascade structure algorithm which combined with adaptive Kalman algorithm was proposed for the fading channel. The timevarying channel could be fully tracked by the proposed algorithm， and the detection error diffusion in detection process was able to be avoided. In addition， the purpose of MAI suppression was achieved. Simulation results showed that the proposed algorithm is of better convergence， dynamic tracking ability and algorithm precision， therefore， it is an effective interference cancellation MUD algorithm. References | Related Articles | Metrics

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Long Time Span Face Recognition Based on SFLA LI Gen， LI Wenhui 2014, 35 (7):  955-959.  DOI: 10.12068/j.issn.1005-3026.2014.07.010 Abstract ( 700 )   HTML   PDF (399KB) ( 680 )   The long time span invariable feature(LTSIF)and short time span invariable feature(STSIF)exist in face features. A method was proposed to classify the two types of features， then the LTSIF was used to recognize the long time span face image. First， the bestdivide method was replaced by the bestcoverage method to normalize the features based on shuffled frog leaping algorithm(SFLA). Second， the normalized featureweight and basevalue was calculated by the time span and the featurevariability to classify the LTSIF and STSIF. In the recognition process， the featureweight and basevalue were refreshed with the recognized face image to recognize the long time span face images. The results indicated that over 82% face images can be recognized by the proposed method in years’ time span， which was better than other algorithms. References | Related Articles | Metrics

Materials & Metallurgy

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Dynamic Recrystallization Behaviors of High Performance Bridge Steels with Lower Ni，Cr，Cu and Mo Contents CHEN Jun， TANG Shuai， LIU Zhenyu， WANG Guodong 2014, 35 (7):  960-964.  DOI: 10.12068/j.issn.1005-3026.2014.07.011 Abstract ( 585 )   HTML   PDF (1125KB) ( 601 )   The dynamic recrystallization behaviors of high performance bridge steel with lower Ni， Cr， Cu and Mo contents were investigated using single pass compression tests. At the same time， the true stresstrue strain curves were fitted and smoothed using a ninthorder polynomial in order to eliminate fluctuations in experimental curves， and the strain hardening rate vs true stress curves under different conditions were determined. The characteristics of the strain hardening rate vs true stress curves show that the dynamic recrystallization has occurred for different hot compression deformation processes studied. The constant α was modified as 0009MPa-1， the dynamic recrystallization activation energy was gained， the relationship of εc =063εp was determined and the critical strain model for predicting dynamic recrystallization initiation was established. Moreover， the dynamic recrystallization activation energy was significantly lowered with reducing Ni， Cr， Cu and Mo contents. Related Articles | Metrics

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Ternary Compound and Relative Phase Equilibria in the LowTi Side of NbNiTi System LI Zhichao， LI Hongxiao， REN Yuping， QIN Gaowu 2014, 35 (7):  964-967.  DOI: 10.12068/j.issn.1005-3026.2014.07.012 Abstract ( 581 )   HTML   PDF (2509KB) ( 644 )   The phase transformation and phase equilibria related with the ternary compound XB in the lowTi side of NbNiTi system were systemically investigated through the equilibrated alloy method by using the scanning electron microscopy(SEM)assisted with energy dispersive spectroscopy of Xray(EDS)， electron probe microanalysis(EPMA)， Xray diffraction(XRD)and differential scanning calorimetry(DSC). It has been shown that the threephase field XB+(Nb)+TiNi exists at both 1000℃ and 1100℃ isothermal sections of the phase diagram in the NbNiTi system. The compound XB could be in solidstate equilibrium with the Nbbased solid solution(Nb)and the TiNi phase till about 1133℃. There exists the eutectic phase transformation LTiNi+XB at 1133℃ in the NbNiTi system. As the liquid forms， the compound XB could not be in equilibrium with the Nbbased solid solution and the TiNi phase. The threephase field XB+(Nb)+L exists at 1150℃ isothermal sections of the phase diagram in the NbNiTi system， XB keeps phase equilibrium with the liquid and the Nbbased solid solution. References | Related Articles | Metrics

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Numerical Simulation on Cladding Casting of Composite Ingot HAN Xing， SHAO Bo， ZHANG Haitao， CUI Jianzhong 2014, 35 (7):  969-974.  DOI: 10.12068/j.issn.1005-3026.2014.07.013 Abstract ( 656 )   HTML   PDF (1480KB) ( 752 )   A mathematical model was developed to describe the process of cladding casting of 4045/3003 composite ingot. The flow field and temperature field in the casting process were simulated to investigate the effect of casting speed on flow field and temperature field， which was also compared with temperature measurements during the process of cladding casting. The results showed that proper increasing the casting speed can contribute to the compounding of two alloys， but excessive speed will make the supporting outer surface so hot and thin that the interface remelted and thus the test failured. The reasonable casting speed for a smooth cladding casting is 100mm/min. Moreover， there is a good agreement between the calculated results and the measured results. The interface microstructure shows that the bonding of two different alloys are metallurgical bonding. The simulated results can predict whether the two alloys could composite together successfully or not， which provides a scientific guidance for optimizing the process of cladding casting. Related Articles | Metrics

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Recognition Method of the Molten Steel Level in the Strip Casting Process Based on the Machine Vision LI Jiadong， WANG Zhaodong， CAO Guangming， WANG Guodong 2014, 35 (7):  974-977.  DOI: 10.12068/j.issn.1005-3026.2014.07.014 Abstract ( 635 )   HTML   PDF (711KB) ( 665 )   A recognition method based on the machine vision was designed and investigated to solve the problem on the measurement of molten steel level in the strip casting processing. Based on the different image grey values captured by linear CCD camera between the molten steel and casting rolls， a machine vision system for measuring molten steel level was designed. By the high speed character of the linear camera image data acquisition， a method to create molten steel level original image by the time was proposed and the molten steel level recognition model was established building with filtering， binarization and boundary recognition as the core. The system and model were tested on a smallscale strip casting machine and the induction furnace respectively. The results illustrate that the molten steel level detection system and its recognition method are feasible， which show high levels of the precision and response speed and can be applied in the industrial line for the strip casting. References | Related Articles | Metrics

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Comparison of the Rolling Speed and Water Flow Adjusting on the Finishing Rolling Temperature Control GONG Dianyao， CHEN Huaxin， XU Fang， XU Jianzhong 2014, 35 (7):  979-983.  DOI: 10.12068/j.issn.1005-3026.2014.07.015 Abstract ( 653 )   HTML   PDF (702KB) ( 750 )   Based on the commission of the finishing rolling temperature control model of some domestic hot strip rolled mill， the principles of the temperature control by using rolling speed and water flow adjusting were introduced respectively. The measured curves of the rolling speed， water flow adjusting and finishing temperature by using the two means as mentioned previously on rolling typical products were compared. Furthermore， the difference of finishing temperatures controlled by using different control means were discussed in detail. At the same time， referring to the tracking principle of cooling control model on runout table， the effect of rolling speed adjusting on the following cooling control after rolling was analyzed. The results showed that more accurate finishing rolling temperature control was obtained by the rolling speed adjusting method than by the water flow adjusting method， however， water flow adjusting helped to get smooth rolling speed curve and was beneficial to promoting the cooling control after rolling. References | Related Articles | Metrics

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Distribution Ratio of Niobium and Phosphorus Between Slag and Iron in the MeltingSeparation Process ZHANG Bo， LI Chunlong， JIANG Maofa 2014, 35 (7):  983-986.  DOI: 10.12068/j.issn.1005-3026.2014.07.016 Abstract ( 733 )   HTML   PDF (783KB) ( 661 )   The slagiron system which was formed in meltingseparation process of the prereduction niobium concentrate of Bayan Obo with electric furnace was taken as a research object. The variation rule of the distribution ratio of niobium and phosphorus between the slag and iron during the meltingseparation process was investigated by experiment. The results showed that the distribution ratios of niobium and phosphorus decreased with the increase of w［C］， and w［C］should be controlled below 342% at end point of the meltingseparation process. The niobium oxides was reduced to NbC at the slagiron interface when carbon dissolved in iron saturated. The distribution ratios of niobium and phosphorus decreased with the increase of temperature， the temperature should be controlled at 1450℃ in the meltingseparation process. The distribution ratios of niobium and phosphorus increased with the increase of w(FeO)，and w(FeO)should be 585% at end point of the meltingseparation process. The distribution ratios of niobium and phosphorus increased with the increase of the optical basicity of the slag， the addition of MgO in slag greatly decreased the distribution ratio of phosphorus. References | Related Articles | Metrics

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Composition and Formation Mechanism of Viscous Layers in Blast Furnace Hearth JIAO Kexin， ZHANG Jianliang， ZUO Haibin， ZHAO Yongan 2014, 35 (7):  987-991.  DOI: 10.12068/j.issn.1005-3026.2014.07.017 Abstract ( 651 )   HTML   PDF (1268KB) ( 1350 )   The formation mechanism of the viscous layer in the blast furnace hearth was studied through chemical analysis， XRD， SEMEDS analysis and the carbon composite brick property test. The results showed that the carbon composite brick has excellent anticorrosion properties to the iron and slag because of its dense microstructure. Furthermore， it has selfprotection function by formation the multiphase system consisted of the graphiteC layer， high alumina slag layer and the graphite layer. The thermodynamic condition of the graphite precipitation on the sidewall of the hearth was calculated. Under a certain flow condition of the molten iron， there was a dissolution and precipitation equilibrium between the graphite precipitation and the molten iron. Thereby， the graphite separated the direct contact of the molten iron from the brick. Then the erosion of the brick slowed down and the long service life of the blast furnace was achieved. References | Related Articles | Metrics

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Compensation Identification for Total Heat Exchange Factor YI Zhi， ZHANG Weijun， CHEN Haigeng 2014, 35 (7):  992-995.  DOI: 10.12068/j.issn.1005-3026.2014.07.018 Abstract ( 615 )   HTML   PDF (662KB) ( 615 )   The total heat exchange factor(CF)is the important parameter for the L2 control system of reheating furnace. CF is influenced by the furnace structure parameters and operating parameters. So the compensation identification for CF is very important. The solo ternary model based on the furnace temperature was developed. Taking any model section of a ternary model， the temperatures of the furnace and of the slab surface were used as input conditions， the thermocouple model was developed and the energy equations of the thermocouple and furnace wall were established. Finally， the heat flux of slab surface was solved. So the identification for CF was researched. The influences for CF by the temperature， size of slab and the temperature change of the slab were researched. The results demonstrated that the value of CF decreased with the increase of the slab temperature， when the furnace temperature was constant. When the slab temperature was closed to the furnace temperature， the absolute value of the gradient for the variation of CF increased rapidly. While the slab temperature was constant， the value of CF increased with the increase of furnace temperature. Moreover， the CF increased with the increase of the length and width of the slab， and also increased with the increase of the emissivity for the slab. References | Related Articles | Metrics

Mechanical Engineering

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Dynamic Simulation of Spur Gears with Assembly Errors and Machining Errors TONG Cao， SUN Zhili， MA Xiaoying， CHAI Xiaodong 2014, 35 (7):  996-1000.  DOI: 10.12068/j.issn.1005-3026.2014.07.019 Abstract ( 757 )   HTML   PDF (1257KB) ( 953 )   According to the definition and description of error in the gear precision standard， an equivalent definition of assembly errors and machining errors was proposed for the gear dynamic analysis. A gear parametric model with assembly errors and machining errors was established by Pro/E secondary development. Then the gear finite element model was created based on dynamic contact mechanics and explicit dynamic finite element method. Finally， its dynamic simulation was conducted using the large deformation explicit dynamics software ANSYS/LSDYNA， thus the the calculation for gear contact stress on tooth contact was available to consider the effects of assembly errors and machining errors. Results showed that the larger all kinds of random errors are， the greater the impact of the gear contact stress are. Of all kinds of random errors， the effects of gear machining error and misalignment error on the plane of action are the most obvious， while the misalignment error on the vertical plane of action exerts the least effect on the gear contact stress. The most significant fluctuation of tooth contact stresses appears when the assembly errors and machining errors both exist. References | Related Articles | Metrics

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Dynamic Load Calculation of Excavator Hoisting System LIN Guiyu， LI Jie， LIAN Jinhua， REN Yuelong 2014, 35 (7):  1001-1003.  DOI: 10.12068/j.issn.1005-3026.2014.07.020 Abstract ( 700 )   HTML   PDF (350KB) ( 585 )   Considering the complexity of the dynamic load calculation using the multidegreeoffreedom model for the hoisting system of the excavator， initially， the driving parts of hoisting system， such as axle， gear， coupling and structural parts， were taken as rigid component， only left the hoisting wirerope taken as elastic component without taking the damping effect into consideration. A twodegreeoffreedom model was put forward by simplifying the multidegreeoffreedom model for excavator’s hoisting system. Under the lockedrotor conditions where arm is perpendicular to the movable arm and the bucket rod is completely out of position， the dynamic load coefficient of the hoisting system was calculated by the Lagrange equation method， and compared with the coefficient from the multidegreeoffreedom model. The result shows that the twodegreeoffreedom model can be used instead of the multidegreeoffreedom model to simplify the calculation in the preliminary design stage. References | Related Articles | Metrics

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Mixed Lubrication Characteristics of Cold Rolling Process FU Kuo， ZANG Yong， GAO Zhiying 2014, 35 (7):  1005-1010.  DOI: 10.12068/j.issn.1005-3026.2014.07.021 Abstract ( 534 )   HTML   PDF (533KB) ( 680 )   Based on the surface asperity distribution hypothesis of Christensen and the theory of rolling and hydrodynamics， a mixed lubrication model was set up for cold rolling process in which surface roughness is taken into consideration. The mixed film lubrication constraint relation was also proposed to judge the friction condition. The distribution of film thickness， contact area ratio， pressure stress and friction stress were simulated and analyzed under different conditions using this model. The results showed that larger reduction results in a thinner film thickness， larger contact area ratio of the interface and higher stress. Surface roughness was shown to have a pronounced effect on the contact area ratio and the stress distribution. As the surface roughness increases， the contact area ratio， as well as pressure stress and friction stress， would increase. Higher viscosity lubricant or roll speed can reduce the friction and the rolling force effectively. Related Articles | Metrics

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Influence of Small Depth Cut on Grinding Surface Microstructure Damage and Mechanism ZHANG Xiuming， XIU Shichao， SHI Xiaoliang， LIU Minghe 2014, 35 (7):  1010-1013.  DOI: 10.12068/j.issn.1005-3026.2014.07.022 Abstract ( 638 )   HTML   PDF (950KB) ( 634 )   In view of grinding surface microstructure damages under small depth cut， the connection between ground residual stress and microcrack was theoretically analyzed. Surface residual stress and its cloud distribution were simulated under different ground conditions for 45 steel workpieces using finite element analysis， and then effects of grinding depth and cooling conditions on the grinding surface residual stress were discussed. At last， grinding experiments were conducted for 45 steel workpieces under different conditions to verify the simulation results by measuring the specimen surface residual stress. At the same time， the grinding surface microstructures with different grinding parameters were studied using SEM. The test results show that adopting appropriate grinding parameters and conditions can effectively reduce and avoid the grinding surface microstructure damages. References | Related Articles | Metrics

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Experimental Study on Influencing Factors of Disc Cutter Performance WANG Zhaoqian， WANG Jiye， ZHANG Zhimin， GUAN Zhenhua 2014, 35 (7):  1015-1018.  DOI: 10.12068/j.issn.1005-3026.2014.07.023 Abstract ( 545 )   HTML   PDF (912KB) ( 521 )   The rockbreaking performance was studied in the liner cutting test based on different cutting parameters， especially on penetration depth， cutting speed and cutter space. The test results show that the rockbreaking force is increased with the penetration depth and cutting speed. The optimal penetration depth and cutting speed are 76mm and 6m/h in current project. Both the total thrust and torque could be calculated from the maximum linear velocity and rotating speed of cutter head. Attrition crushing was occurred and powder district was formed in the front side of the disc cutter， while the sides will be under the extrusion force and gradually reach the ultimate strength of shear leading to fragmentation. References | Related Articles | Metrics

Resources & Civil Engineering

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Preparation and RoomTemperature NO2 Sensing Properties of TeO2 Nanowires SHEN Yanbai， WEI Dezhou， MA Jiawei， ZHANG Baoqing 2014, 35 (7):  1019-1022.  DOI: 10.12068/j.issn.1005-3026.2014.07.024 Abstract ( 518 )   HTML   PDF (1829KB) ( 929 )   TeO2 nanowires were synthesized on Aucoated Si substrate by thermal evaporation using Te metal as the source material. The gas sensor was prepared by using TeO2 nanowires as the sensing material. Microstructural characterization by means of XRD， SEM and TEM showed that TeO2 nanowires were single phase of tetragonal structure. The nanowires were approximately several tens of micrometers in length and 80~600nm in diameter. No Au particles existed at the top of TeO2 nanowires， revealing that the growth of TeO2 nanowires occurred in vaporsolid mechanism. The gas sensing measurements indicated that TeO2 nanowires showed a ptype electrical conduction and reversible response to NO2 gas at room temperature. The sensitivity showed a linear increase with the increasing of NO2 gas volume fraction. The gas sensing mechanism of TeO2 nanowire sensor was investigated preliminarily. References | Related Articles | Metrics

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Kinetic Analysis on Preparation of Micro Power Aluminum Hydroxide by Liquid Precipitation Process WANG Peng， WEI Dezhou 2014, 35 (7):  1023-1028.  DOI: 10.12068/j.issn.1005-3026.2014.07.025 Abstract ( 620 )   HTML   PDF (2065KB) ( 935 )   Response surface methodology and kinetic analysis were introduced to study the process of cultivating micro power aluminum hydroxide by liquid precipitation process. The results from the response surface methodology show that the most important factor influencing median diameter is the reaction temperature， followed by reaction time， amount of dispersant and pH value， and the most important factor influencing fractal dimension is the amount of dispersant， followed by the pH value， reaction temperature and reaction time. According to the analysis of kinetics， aluminum sulfate and ammonia reaction process is divided into the crystal nucleus growth and grain growth period. The equations of crystallization kinetics accord with the secondorder reaction rate equation， and the apparent activation energy are 051 and 127kJ/mol， respectively. Crystal growth mechanism research indicates that diffusion control mechanism determines the crystal nucleus growth and crystal grain growth. References | Related Articles | Metrics

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Dephosphorization Effect of Sodium Carbonate in the Process of Direct Reduction Roasting of High Phosphorous Oolitic Hematite XU Yan， SUN Tichang， LIU Zhiguo， XU Chengyan 2014, 35 (7):  1028-1032.  DOI: 10.12068/j.issn.1005-3026.2014.07.026 Abstract ( 659 )   HTML   PDF (1122KB) ( 840 )   In order to investigate the effects of sodium carbonate on magnetic concentration and dephosphorization in direct reduction roasting process of a high phosphorous oolitic hematite from Nigeria， the products of direct reduction roasting were analyzed by Xray diffraction(XRD) and scanning electron microscopy(SEM) after sodium carbonate was added. The results showed that the dephosphorization can be realized in the reduction roasting process after the sodium carbonate was added:sodium carbonate added inhibits the formation of fayalite and interdicts the process of the phosphorus entering metallic iron; the oolitic structure is destroyed， promoting aggregation and growth of metallic iron particles and the liberation of metallic iron particles from gangue; phosphorusbearing minerals in the raw ore can react with sodium carbonate in the process of roasting， so that soluble complex sodium phosphate is generated， which is soluble in water in the process of grinding and magnetic separation and lower phosphorus content of direct reduction iron. References | Related Articles | Metrics

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Analysis of Bacterial Diversity in Oil Shale by PCRDGGE with Different 16S rDNA Target Sequences JIANG Shaoyan， WANG Wenxing， XUE Xiangxin， YANG Shouhao 2014, 35 (7):  1033-1037.  DOI: 10.12068/j.issn.1005-3026.2014.07.027 Abstract ( 782 )   HTML   PDF (2127KB) ( 790 )   For a comprehensive understanding of bacterial community structure of the oil shale from Fushun west openpit mine in China and screening out best prime for PCRDGGE analysis of oil shale， an improved SDShighsalt extraction method was used to extract microbial total DNA from the oil shale. Fourset primers (968F/1401R， 338F/518R， 341F/907R and 1055F/1406R) of 16S rDNA high variable target regions， V6V8， V3， V8， V9， were compared to obtain the optimal target sequences suitable for PCRDGGE. The results from PCRDGGE patterns showed that fourset primers can amplify the target sequences， but different target sequences of primers have a significant effect on the detection of the bacterial diversity (P<0001). Compared with the other primers， 968F/1401R and 338F/518R are more suitable for the bacterial diversity analysis of oil shale samples due to higher fingerprint species richness and abundant bacteria group obtained from their PCRDGGE. The community structure of bacteria in oil shale is not much rich. Acinetobacter， Pseudomonas and Escherichia are the dominant bacterial communities， as well as some unidentified bacterium which belong to Pseudomonadales and Enterobacteriales. References | Related Articles | Metrics

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Geochemical Characteristics of Mineralization Rock from the Luming Molybdenum Deposit in Heilongjiang Province ZHANG Chunpeng， WANG Ende， BI Zhongwei， CHEN Jiang 2014, 35 (7):  1039-1042.  DOI: 10.12068/j.issn.1005-3026.2014.07.028 Abstract ( 668 )   HTML   PDF (314KB) ( 582 )   The Luming molybdenum deposit occurs in early Yanshanian pluton consisting of adamellite and granite porphyry. The data of petrography and geochemistry show that the SiO2 content varies from 6384% to 7132%， total alkali content varies from 69% to 84%， and w(K2O)/w(Na2O) has an average value of 137. Most of the rocks belong to metaluminousperaluminous high potassium calcallkaline granite. The rocks have high total REE content. LREE is relatively enriched. The chondritenomalized REE patterns show that the curves of REE are right dip types with slightlymoderate negative Eu anomalies. The adamellite and granite porphyry magma which relates to mineralization belong to A2 type granite formed by the crust material source magma evolution. It is inferred that the pluton was formed by the conversion from a postcollisional environment to an extensional environment. References | Related Articles | Metrics

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Effect and Mechanism of Stenotrophomonas Strain USTB2 as Collector for Hematite YANG Huifen， TANG Qiongyao， LI Tian， WANG Chuanlong 2014, 35 (7):  1042-1045.  DOI: 10.12068/j.issn.1005-3026.2014.07.029 Abstract ( 546 )   HTML   PDF (1258KB) ( 599 )   A nonpathogenic stenotrophomonas strain USTB2 was screened out from the soil of Sijiaying iron ore plant and studied as collector for hematite by flotation tests. Zeta potential measurement results showed that the bacteria was negatively charged in the large range of pH. The contact angle of hematite increased by 3395° and surface hydrophobicity of hematite was greatly improved after interaction with USTB2 strain. The flotation recovery of hematite could reach to 7631% at pH=6 and the bacterial cells addition amount of 60g/t. The mechanism study results showed that the outer surface of USTB2 cell has hydrocarbon groups， carboxyl groups and phosphoric acid groups， so the bacteria has similar characteristics of fatty acid collector， and can form the flocs between hematitehematite particles by the “bridge” action. This is confirmed that the stenotrophomonas strain USTB2 can work as collector for hematite. References | Related Articles | Metrics

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Prediction of the Fragments Initial Velocity in Tank Explosions Accident PAN Ke， XU Kaili 2014, 35 (7):  1047-1050.  DOI: 10.12068/j.issn.1005-3026.2014.07.030 Abstract ( 746 )   HTML   PDF (550KB) ( 847 )   Two prediction methods were established based on the penetration experiments and theoretic analysis to rationally determine the initial velocity of the fragments. The initial velocity prediction model based on the initial kinetic energy was established by the total explosion energy and energy transferred factor. The total energy for the physical explosion of compressed gas tank and runaway reaction explosion can be estimated by Baum equation， while overheated energy as total energy produced by overheated liquid in BLEVE is more rational. The energy probability density transferred factor was obtained by the existing data collected from experiments of Baum， Birk， industrial explosions and maximum entropy principle. The results show that the probabilistic density of energy transferred factor is gamma distribution. Using the presented method， the initial velocity for the quantitative assessment of the explosion fragments can be predicted effectively. References | Related Articles | Metrics

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Study of Iterative Methods for TimeDependent Stokes Equations SHEN Hailong， LI Xiaosha， SHAO Xinhui 2014, 35 (7):  1051-1053.  DOI: 10.12068/j.issn.1005-3026.2014.07.031 Abstract ( 492 )   HTML   PDF (313KB) ( 625 )   The solution to the timedependent Stokes equations has broad application in physics， discrete dynamic system， scientific computing， and other fields.However， the equations are timedependent partial differential equations and very difficult to solve in practice. To solve this problem， a new dual preconditioned method was firstly constructed based on preconditioned technology. Then their iterative formats， convergence domains and the corresponding conclutions were given. The convergence rate of the iterative method was improved by modifying the parameters in the iterative method and preprocessing on the equations themselves. Finally， the feasibility and effectiveness of the dual preconditioned iterative method were verified with numerical examples. References | Related Articles | Metrics

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An Improved Traffic Flow Model SHAO Xinhui， HAN Ying， HU Yunyi 2014, 35 (7):  1055-1058.  DOI: 10.12068/j.issn.1005-3026.2014.07.032 Abstract ( 1261 )   HTML   PDF (708KB) ( 1225 )   To better carry out the planning and control of urban transport， a more effective mathematical model describing traffic flow was given. The new model is based on both the driver’s carfollowing behavior and general linkage between microscopic and macroscopic parameters. Since the model includes the effects of both the relative speeds and the relative distance with linear weighted method， it is more realistic. Meanwhile， some wellknow continuum models are contained in this new model as special cases， such as Payne model， Wiltham model， and Zhang model. The characteristic velocity and linear stability of the new model were studied. The new model is inherently stable and controls the extent of nonanisotropic and diffusive influences through a dimensionless parameter called anisotropic factor. References | Related Articles | Metrics

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Hopf Bifurcation Control of the Qi System Based on State Feedback and WashoutFilter〓 ZHANG Zhonghua， YUAN Huiqun 2014, 35 (7):  1059-1063.  DOI: 10.12068/j.issn.1005-3026.2014.07.033 Abstract ( 612 )   HTML   PDF (1091KB) ( 600 )   To control the Hopf bifurcation of a Qi system， the Hopf bifurcation type was firstly determined by bifurcation stability index. Then， the state feedback controller and Washout filteraided feedback controller were designed to control the Hopf bifurcation， respectively. The effects of controller parameters on the bifurcation position and the amplitude of limit cycle were discussed based on the Normal Form method. Simultaneously， the simulations using Matlab software were carried out to illustrate the results. Simulation charts and theoretical results show that the linear gain can change the position of Hopf bifurcation and even eliminate Hopf bifurcation， while the nonlinear gain can change the bifurcation type of original system. Finally， some conclusions were obtained with a comparison between the state feedback controller and the Washout filteraided ones.The results showed that the control effect based on Washout filter is better than the effect based on nonlinear state feedback controller. References | Related Articles | Metrics