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31 July 2017, Volume 51 Issue 7 Previous Issue    Next Issue

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Numerical Simulation of Axially Loaded Circular Steel Tubular  Stub Columns with Fly Ash Concrete Infill ZHANG Yang1,2,CHEN Bing1,ZHAO Shexu1,LI Siping1 2017, 51 (7):  769-773.  Abstract ( 589 )   Save  Based on the experimental study on the circular fly ash concrete filled steel tubular stub columns, a constitutive relation model of confined fly ash concrete for finite element analysis is proposed by regression analysis and repeated calculations. The validity of the constitutive relation model is verified through the finite element method analysis. The constitutive relation model is suitable not only for the numerical analysis of fly ash concrete filled steel tubes, but also for that of ordinary concrete filled steel tubes. The research is helpful for the numerical simulation of fly ash concrete filled steel tubes. References | Related Articles | Metrics

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Redundancy Investigation of PreTensioning CableStrut Systems  Considering the Effect of PreStresses ZHOU Jinyu,CHEN Wujun,HU Jianhui,ZHAO Bing,WANG Lijun 2017, 51 (7):  774-780.  Abstract ( 541 )   Save   A unified redundancy formulation for both the elastic redundancy and the geometrical redundancy is proposed to be applicable for cablestrut systems at prestressed state by considering the effect of prestresses. The updated Lagrange formulation is used to establish a nonlinear description of strain energy with respect to the displacement increment; a common linearization method is then adopted to reduce the numerical complexity. Based on this reasonable simplification, a unified evaluation for the redundancy is derived by using the principle of minimum potential energy, which is interpreted as a useful method for system identification at prestressed configuration. In comparison with existing studies, an explicit formula of geometrical redundancy is firstly presented and the physical meanings of redundancy are clearly addressed. Furthermore, it can be concluded that this proposed evaluation is valid for cablestrut systems with introduced pretensions. References | Related Articles | Metrics

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Methods of TetranButyl Ammonium Bromide Clathrate Hydrate  Slurry Generation in Cold Storage AirConditioning BAI Ziyu,SHI Xinjie,ZHANG Peng 2017, 51 (7):  781-786.  doi: 10.16183/j.cnki.jsjtu.2017.07.003 Abstract ( 779 )   Save  Tetranbutyl ammonium bromide (TBAB) clathrate hydrate slurry (CHS) has shown a promising application prospect in cold storage airconditioning. In the present study, TBAB CHS was generated from 20% (mass fraction) initial concentration aqueous solution in a cold storage airconditioning. Three TBAB CHS storage methods, i.e., homogeneous, heterogeneous and heterogeneous with filter, and two methods of melting the crystal layer on the wall of the heat exchanger determined by fixed time and by flowrate were utilized to generate TBAB CHS. Temperature, flowrate, pressure drop, image of TBAB CHS and coefficient of performance were obtained during the generation processes. It was found that heterogeneous with filter can enhance the efficiency up to 14.3% and 9.8% compared with the homogeneous and heterogeneous methods, respectively. References | Related Articles | Metrics

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Combustion and Particle Emission Characteristics Affected by  Fuel Supply Parameters for a Diesel Engine Fuelled with  Polyoxymethylene Dimethyl Ethers/Diesel LIN Da,ZHU Yijia,WEI Xiaodong,WANG Zhiyu,ZHANG Wugao 2017, 51 (7):  787-795.  doi: 10.16183/j.cnki.jsjtu.2017.07.004 Abstract ( 813 )   Save  The research tested the effect of fuel supply parameters on combustion and particle emission characteristics on a diesel engine fueled with neat diesel and blends of polyoxymethylene dimethyl ethers (PODE)/diesel (φPODE=20%). The results showed that the increase of common rail pressure could cause advanced main fuel heat release, higher peak incylinder pressure and higher mean gas temperature; the increased common rail pressure would decrease accumulation mode particle (AMP) emission, but would increase nucleation mode particle (NMP) emission under lightduty mode. The advanced pilot injection timing would lower the pilot fuel heat release, and improve the main injection heat release under low load; the advanced pilot injection timing would effectively reduce the AMP number concentration, but cause obvious NMP number increase. The advanced main injection timing directly shifted the main fuel heat release rate and caused an advanced, increased pressure peak; earlier main injection timing would cause lower AMP number concentration and higher NMP emission under lowduty mode, and obtained opposite results under highduty mode. The introduction of PODE could amplify the positive effect of fuel supply parameters on particle emissions and suppress the NMP emission to a certain extent. References | Related Articles | Metrics

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Effects of Injection Strategy and Operation Parameters on  Particle Emission of Gasoline Direct Injection Engine ZHUANG Zhuyue,ZHAO Tingyu,FANG Junhua,HUANG Zhen 2017, 51 (7):  796-804.  doi: 10.16183/j.cnki.jsjtu.2017.07.005 Abstract ( 743 )   Save   A DMS500 fast particulate spectrometer was employed to characterize the particle size distribution for a naturally aspirated gasoline direct injection (GDI) engine. The goal is to investigate the impact of engine operating parameters (load condition, coolant temperature, spark timing), injection strategies (start of injection, fuel pressure) on particulate size distribution and particle number, and thermogravimetric analyses of particulate matters in different load conditions.The experimental results show that, particulate size distribution is bimodal in form with nucleation mode particle and accumulation mode particle, depending on nucleation mode at low load or accumulation mode at high load. Cold coolant temperature produces higher particulate matter emission. With delay of spark timing, the particle number is reduced. An optimized injection timing valve has been found based on operation conditions. Fuel pressure has a significant effect in particle number, high fuel pressure reduces particle number and increases nucleation mode percentage. With increases of load, and decrease of coolant temperature, the maximum mass loss rate temperature of soot increases and soot oxidation activity reduces. References | Related Articles | Metrics

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Analysis of Dynamic Mode Decomposition for  Wind Turbine Airfoil Flow Field at High Angle of Attack LIU Pengyin1，2,CHEN Jinge1,SHEN Xin1,ZHU Xiaocheng1,DU Zhaohui1 2017, 51 (7):  805-811.  doi: 10.16183/j.cnki.jsjtu.2017.07.006 Abstract ( 919 )   Save  The unsteady flow field is calculated by the computational fluid dynamics (CFD) method, around a wind turbine airfoil at high angle of attack, and its modes are identified by using the dynamic mode decomposition (DMD) method. The dominant modes and corresponding frequencies are obtained. The results show that the DMD method can be used to analyze the changing process of the unsteady flow field; the DMD modes capture the main flow structure of the unsteady flow field, and the main unsteady flow is around the near wake region; the flow field, reconstructed by 4 DMD modes, could describe the original unsteady flow field; the flow field reconstructed by the second DMD mode describe that two vortexes, whose rotating directions are opposite, shed and spread into downstream in turn. References | Related Articles | Metrics

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Experimental Study of LType Podded Propulsors in  Straight Forward Motion and Azimuthing Conditions ZHAO Dagang1,GUO Chunyu1,SU Yumin1 DOU Pengfei2,JING Tao1,ZHANG Haipeng1 2017, 51 (7):  812-818.  doi: 10.16183/j.cnki.jsjtu.2017.07.007 Abstract ( 924 )   Save  In this study, an openwater measuring instrument was developed for Ltype podded propulsors and a series of experimental tests were conducted to evaluate hydrodynamic performances of the podded propulsor. Performance of propeller thrust, torque and overall thrust of the podded propulsor unit was measured in the experiment under the conditions of straight forward motion with the advance coefficient between 0 and 1.3. And a comparison of propeller and the podded unit performance under dynamic azimuthing conditions with an azimuthing of 0.1396 rad/s and static azimuthing conditions was made at three different advance coefficients of Ltype podded propulsors. The experimental results demonstrated that comparing with the static azimuthing conditions, propeller thrust in dynamic azimuthing conditions was larger but torque was smaller when the Ltype podded propulsor with righthanded rotation propeller turns right. The regularity of the variable force on the pod is very complex. References | Related Articles | Metrics

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Simulation of Two Degrees of Freedom VortexInduced Vibration by  Using Improved Shear Stress Transport Model NI Wenchi1,2，KANG Zhuang1，ZHANG Cheng1，ZHANG Lijian1 2017, 51 (7):  819-825.  Abstract ( 639 )   Save   According to the existing literature, the calculated results of numerical simulations of two degrees of freedom (DoFs) vortexinduced vibration with low mass ratio of column are not ideal. Especially, the maximum vibration amplitude is significantly smaller than the experimental value. In this paper, based on open source software OpenFOAM, the standard shear stress transport (SST) turbulence model and numerical simulation method are improved. Then, the vortex induced vibration of a cylinder with a mass ratio of 2.6 and a doubleDoF from 2 to 14 is simulated by the sweep frequency method, and the results of numerical simulation are analyzed and compared. Results show that the numerical simulation results of the improved SST turbulence model can be more close to the experimental data, and the sweep frequency method can better reflect nonlinear characteristics of the vortexinduced vibration. References | Related Articles | Metrics

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Research on an Integral Steady Panel Method for  ContraRotating Propeller ?WANG Rui，XIONG Ying 2017, 51 (7):  827-830.  Abstract ( 643 )   Save  he geometry of contrarotating propeller was discussed and the basic theory of surface panel method was analyzed. Then an integral steady panel method which treats the forward propeller and aft propeller as a whole was presented. Two sets of contrarotating propeller developed by David W. Taylor Naval Ship R&D Center were analyzed by the integral steady panel method. Numerical results were compared with experimental data and iterative panel method results. Results show that the calculation time of integral steady panel method is nearly half as much time of iterative panel method’s and the accuracies are equal. As the iterative procedure is avoided in the integral steady panel method, an efficient method can be established based on the integral steady method for the design and analysis of contrarotating propeller or hybrid CRP podded propulsion system. Furthermore, the numerical error of integral steady panel method was analyzed. References | Related Articles | Metrics

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Nonlinear Numerical Investigation on the Interaction of  Focused Waves with Very Large Floating Structure CHENG Yong1,JI Chunyan1,LU Tingting1,ZHAI Gangjun2 2017, 51 (7):  831-839.  doi: 10.16183/j.cnki.jsjtu.2017.07.010 Abstract ( 1058 )   Save  This paper establishes a twodimensional fully nonlinear numerical wave tank for studying the interaction between focused waves and floating elastic plate. The secondorder Stokes wave velocity is given to generate the input wave. The mixed EulerianLagrangian approach is applied to track the transient free and plate surface. A series of modal functions with freeend conditions are adopted to interpolate the displacement, and then the fourthorder RungeKutta scheme is used to refresh profile and velocity potential. The numerical model is verified with existing numerical and experimental results. The effects of the design parameters on the responses are systematically analyzed. References | Related Articles | Metrics

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Visual Analytic System of Vessel Traffic in Bridge Waterway LEI Jinyu1,2,3,CHU Xiumin1,2,HE Wei4,ZHOU Yingping1,2 2017, 51 (7):  840-845.  doi: 10.16183/j.cnki.jsjtu.2017.07.011 Abstract ( 1092 )   Save  Current practice shows that working with bridge waterway automatic identification system (AIS) data often does not lead to insight but rather confusion because large data volume without further being processed is hard to understand. In order to deal with this issue, bridge waterway of Wuhan section in Yangtze River was selected as research area for the study of AIS visualization model and humancomputer interaction method. Additionally, two dimensional kernel density estimation approach was adopted in the heatmap generation to overcome the defects of traditional grid method. Furthermore, based on electric navigation charts, a visual analytics system was built. Finally, three instances were illustrated and results demonstrated that it is conductive to the users in maritime department to make decisions depending on the knowledge they discovered from the visual analytics system. References | Related Articles | Metrics

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Combinatorial Optimization Model of Exclusive Bus Lane and  Transit Signal Priority in the Signal Road Network LU Xiaolin1,PAN Shuliang2,ZOU Nan1 2017, 51 (7):  846-854.  doi: 10.16183/j.cnki.jsjtu.2017.07.012 Abstract ( 959 )   Save  In order to solve the problem of locating exclusive bus lane in the signal road network, this paper presents a combinatorial optimization model of exclusive bus lane location and transit signal priority design. The problem is summarized as a bilevel optimization structure. The upperlevel of the proposed model is designed to solve the integrated design and operation of exclusive bus lane location, lane functional allocation and passive bus priority design with an objective of minimizing the total travel time by car and bus. The lowerlevel of the proposed model is a location model of car users and bus users to minimize the generalized travel cost. A genetic algorithm is developed to solve the proposed model. Numerical analyses have demonstrated the validness of the proposed model. The results also show that the integrated optimization design approach of exclusive bus lane and transit signal priority is preferable to a simply optimizing approach of exclusive bus lane location. And the scientific construction of exclusive bus lane and transit signal priority can maximize the contribution of transit priority strategies to the efficiency of the entire multimodal transportation systems. References | Related Articles | Metrics

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Optimization for Vehicle Scheduling Problem of  Hazardous Materials Transportation Considering Risk Equity CHAI Huo1,2,3,HE Ruichun2,MA Changxi2,DAI Cunjie1,2,3 2017, 51 (7):  855-862.  Abstract ( 787 )   Save   In order to reduce the difference of risk distribution among the populated areas along hazardous materials transportation route, a vehicle scheduling method considering risk equity is proposed when hazardous materials are transported simultaneously between multi origindestination (OD)  pairs. The risk equity evaluation method which reflects the risk difference among all populated area by standard deviation  is proposed firstly. A vehicle scheduling model focusing on risk equity is designed, and the periodic scheduling scheme is obtained to reduce the differences of the accumulation risk in inter regional population so as to achieve a goal of risk equity. For reducing the solution difficulty of the model, a twophase algorithm is proposed after decomposing the model and increasing the interaction among decisionmakers. The example analysis shows that the method can get the optimal vehicle scheduling by adjusting the absolute frequency of vehicles in different routes selection, and can realize the goal of risk equity with the premise of acceptable total cost and total risk. References | Related Articles | Metrics

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Analysis on Influencing Factors of Lateral Stiffness of  Mechanical Elastic Wheel FU Hongxun,ZHAO Youqun,DU Xianbin,WANG Qiang,XIAO Zhen 2017, 51 (7):  864-869.  Abstract ( 891 )   Save  In order to further investigate lateral stiffness properties of mechanical elastic wheel, theoretical and numerical analysis on influencing factors was carried out. Theoretical model of lateral stiffness properties of tire bead unit was established based on energy method, and main factors influencing the wheel lateral stiffness were obtained. On the basis of simplified structure of mechanical elastic wheel, a threedimensional finite element model was established, and the corresponding simulation programs were designed for different vertical loads, structure parameters of tire bead and shear moduli of rubber layer. By using finite element analysis software Abaqus, numerical simulation calculation on lateral stiffness properties of mechanical elastic wheel was completed. And test data of prototype of mechanical elastic wheel were used to verify the validity of the wheel finite element model. The calculation results show that as vertical load or shear modulus of rubber layer increases, lateral stiffness of mechanical elastic wheel increases; with the increase of the depthwidth ratio of tire bead section, the wheel lateral stiffness shows a trend of decrease. Theoretical and numerical research on lateral stiffness of mechanical elastic wheel, reference was provided for optimizing wheel stiffness properties and improving wheel structure. References | Related Articles | Metrics

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Stereo Visual Odometry Based on Robust Features MIN Haigen,ZHAO Xiangmo,XU Zhigang,ZHANG Licheng,WANG Runmin 2017, 51 (7):  870-877.  Abstract ( 732 )   Save  Acquisition of accurate positioning information is a core technology in mobile robots. This paper proposes a stereo visual odometry method based on robust features for robot’s autonomous highprecision positioning. First, a robust feature algorithm AcceleratedKAZE (AKAZE) is adopted to extract the interest points after comparation with other local invariant feature algorithms in three aspects: repeatability, accuracy and efficiency. Then, we present a robust feature matching strategy and the improved Random Sample Consensus(RANSAC) algorithm to remove the outliers which are mismatched features or on dynamic objects. Thus the proposed method can be applied to dynamic environment. Geometry constraint based fractionalstep egomotion estimation algorithm provides the accurate motion of camera rig. Last, we test the presented egomotion scheme on the benchmark datasets of Karlsruhe Institute of Technology and Toyota Technological Institute (KITTI) and data captured on campus in a considerably cluttered environment, and compared with stateoftheart approaches. The proposed approach can restrain the error accumulation and satisfy the requirement of realtime and high positioning system. References | Related Articles | Metrics

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Numerical Simulation and Experimental Study on VortexInduced  Motion of a New Type of Floating Drilling Production Storage Offloading GU Jiayang，XIE Yulin，TAO Yanwu，HUANG Xianghong，WU Jie 2017, 51 (7):  878-885.  Abstract ( 706 )   Save  In this paper, the hydrodynamic characteristics of floating drilling production storage offloading (FDPSO) are studied. The characteristics of vortexinduced motion are studied by the method of combining numerical simulation and model test considering the coupling between different degrees of freedom and the effect of the mooring system. Dynamic mesh technique and Reynoldsaveraged method combined with detached eddy simulation (DES) turbulence model for the NavierStokes equation have been applied to research the flow field characteristics and the threedimensional vortexinduced movement of platform. Simultaneously, in the State Key Laboratory of Ocean Engineering of Shanghai Jiao Tong University, a physical model zoomed with a scale of 1∶80 is used to carry out the experimental study, and the results of model test are compared with numerical simulation. In order to reveal internal mechanism of vortexinduced motion and provide a reference for the design of this type of FDPSO, this paper focuses on the research of time histories of streamwise and transverse motion, spectral characteristics and “lockin” phenomenon. References | Related Articles | Metrics

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Remaining Useful Life Prediction for Hybrid Degradation System DU Dangboa,HU Changhuaa,SI Xiaoshenga,ZHANG Zhengxina,ZHANG Weib 2017, 51 (7):  886-891.  Abstract ( 858 )   Save   In this paper, a hybrid Wienerbased model with stochastic and deterministic parameters is proposed for the degradation path involves an additive of linear and nonlinear part. The remaining useful life (RUL) is an approximant rendered in an explicit form based on the concept of the first hitting time (FHT), and the stochastic and deterministic parameters are estimated by Kalman filter and maximum likelihood estimation method respectively. At last, the effectiveness of the proposed method is proved by the gyro testing data. References | Related Articles | Metrics

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Research of an Intrinsic Motivation Based on the Tropism DAI Lizhen 2017, 51 (7):  892-896.  Abstract ( 565 )   Save  An intrinsic motivation system based on the tropism is presented for the behavioral cognitive problem on the intelligent robot, and the learning evaluation mechanisms and the sensorimotor coordination mechanism are mainly analyzed. The intrinsic motivation is used to build a motion neurocognitive system for a desktop robot realising the learning and cognitive processes like the biological negative phototaxis behavior. The simulation results show the effectiveness of the system. References | Related Articles | Metrics