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30 April 2019, Volume 24 Issue 2 Previous Issue    Next Issue

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Analyzing Spatio-Temporal Distribution Pattern and Correlation for Taxi and Metro Ridership in Shanghai YE Yingwei (叶颖微), SUN Jian* (孙健), LUO Jing (罗京) 2019, 24 (2):  137-147.  doi: 10.1007/s12204-019-2051-0 Abstract ( 450 )   PDF (2839KB) ( 149 )   Taxicab is an important mode in urban transportation system, while the role of taxicabs, especially the relationship with metro system has not been fully studied. This study aims at exploring the factors influencing the role played by taxicabs in Shanghai, China. Firstly, taxi trips are categorized into three types, namely metroreplaceable (MR), metro-extending (ME) and metro-supplement (MS) ones. Then, the tendency of travelers towards taxi or metro at a specific metro station is proposed and calculated on the basis of MR taxi trips and metro trips. Factors influencing the tendency are investigated through semi-parametric regression models, with the results indicating that the most significant factors and the influencing radii during the peak and off-peak hours are different. Some built environment factors, such as the number of hospitals and government agencies, have significant positive relationship with the tendency in the time periods. Furthermore, land use related factors, such as the increase of forestry and commercial land, generally promote taxi-hiring in the off-peak hours, while they have a negative impact during the peak hours. Findings of this study can assist governments and policy makers to understand the impact of built environment and land use on trip patterns, and thus may contribute to more reasonable policies and optimized urban planning, which may promote modal switch from taxi to subway. References | Related Articles | Metrics

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High Efficiency and Quality of Multi-Pass Tandem Gas Metal Arc Welding for Thick Al 5083 Alloy Plates JIANG Zhao (姜朝), HUA Xueming* (华学明), HUANG Lijin (黄立进),WU Dongsheng (吴东升), LI Fang (李芳), CAI Yan (蔡艳) 2019, 24 (2):  148-157.  doi: 10.1007/s12204-018-1977-y Abstract ( 463 )   PDF (8704KB) ( 121 )   Multi-pass tandem gas metal arc welding (TGMAW) for Al 5083 alloy plates with 30mm thickness is carried out to study its high efficiency and high quality. The welding process is evaluated by high-speed photographs and electrical signals. The deposition rate and welding time are calculated to characterize the welding efficiency. The bead formation, porosity, microstructure and mechanical properties are tested and analyzed. The results indicate that though arc deflection occurs due to the electromagnetic interference between two arcs during TGMAWprocess, it does not affect the welding process stability significantly. The deposition rate and welding time of TGMAW process are about 15 g/min larger and about 16.7% less than those of gas metal arc welding (GMAW) process respectively, accompanied by the reduction of heat input. The TGMAW welded joint has less porosity and more refined microstructure to contribute to the improvement of mechanical properties (micro-hardness, tensile strength and ductility). It can be concluded that TGMAW process yields excellent performance of welded joint with improved welding efficiency, which makes it extremely practical during welding of thick plates. References | Related Articles | Metrics

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Effects of Blade Loading Distribution on the Cavitation and Excitation Forces of a Tunnel Thruster YU Cheng (郁程), DONG Xiaoqian (董小倩), YANG Chenjun (杨晨俊), LI Wei (李巍), NOBLESSE Francis 2019, 24 (2):  158-167.  doi: 10.1007/s12204-019-2052-z Abstract ( 426 )   PDF (3909KB) ( 117 )   Compared with open propellers, the impeller of a tunnel thruster is more vulnerable to cavitation and structural vibration problems because the impeller is typically subject to severe non-uniformity of inflow produced by the blunt gearbox. Model tests and numerical simulations are carried out in the cavitation tunnel of Shanghai Jiao Tong University for a tunnel thruster using a “flat plate” impeller and a tip-unloaded one. The characteristics of fluctuating pressures on the tunnel wall and the resultant excitation forces are investigated. It is found that although unloading the blade tips of an impeller is effective in reducing the fluctuating pressures in a local tunnel wall area near the tips, the same trend does not apply to the case of the excitation forces. The results show that care should be taken when the experimentally measured fluctuating pressures are utilized as the input to the analysis of structural vibrations. References | Related Articles | Metrics

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Calculation Method Study on Steel Plate Deformation Under Impulse Loading of Thin Explosive LUO Fang (罗放), ZHANG Shilian* (张世联) 2019, 24 (2):  168-175.  doi: 10.1007/s12204-019-2049-7 Abstract ( 368 )   PDF (1567KB) ( 125 )   Basis of explosion’s responsive analysis and anti-explosion’s structure design is the relation among thin explosive mass, impulse and plate deformation. In this paper, the limitations of theoretical calculation and experimental methods are analyzed according to the relation between impulse loading and deformation of steel plate in thin explosive experiment. The time histories of deformation for the square steel plate under the impulse of thin explosive are calculated by the fluid-solid coupling method and the pressure loading method. The advantages of the pressure loading method and the fluid-solid coupling method are compared. The results show that the steel plate deformation can be estimated accurately using the fluid-solid coupling method when the explosive impulse is unknown, while the theoretical calculation and the pressure loading method provide quick and accurate prediction on the steel plate deformation when the explosive impulse is known. References | Related Articles | Metrics

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Characteristics of the Internal Waves Generated by a Towed Model with Rotating Propeller Under a Strong Halocline DUAN Ningyuan (段宁远), CHEN Ke* (陈科), WANG Hongwei (王宏伟), YOU Yunxiang (尤云祥) 2019, 24 (2):  176-183.  doi: 10.1007/s12204-019-2053-y Abstract ( 362 )   PDF (884KB) ( 120 )   Experiments are performed on the internal waves (IWs) generated by a towed model with rotating propeller in a density-stratified fluid with linear halocline; the Reynolds number ranges from 7 000 to 84 000, and the Froude number ranges from 0.7 to 8.1. The wave speed, amplitude and patterns are investigated on the basis of the multi-channel conductivity probe array technology and the cross correlation analysis method. It is shown that the propeller advances the transition from the body-generated IWs to the wake-generated IWs. Before the transition, the IWs are stationary to the translational model. An extra V-shaped wave with a narrow opening angle is generated by the propeller and the wave amplitude becomes larger with the increase of the thrust momentum, indicating that the propeller produces body and wake effects at the same time before the transition. After the transition, the Froude number associated with the wave speed drops down and fluctuates within 0.4—1.5, showing that the IWs are nonstationary to the model. The interaction of the drag momentum and the thrust momentum changes the characteristics of the wave amplitudes and patterns. The wave amplitude no longer simply grows with the Froude number but depends on the contrast of the drag momentum and the thrust momentum. Experimental results show that the most obvious contrast of the wave pattern contour maps appears when the drag momentum and the thrust momentum have the largest difference if other conditions are the same. When the ratio of the drag momentum to the thrust momentum is within 1—10, the wake can be considered as zero-momentum, meaning that the momentum difference is not enough to generate large scale structures in the wake. References | Related Articles | Metrics

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Calculation Method of Wave Forces on Large Round-Ended Caisson Foundation WEI Chengxun* (韦承勋), ZHOU Daocheng (周道成), OU Jinping (欧进萍) 2019, 24 (2):  184-189.  doi: 10.1007/s12204-019-2054-x Abstract ( 410 )   PDF (3487KB) ( 107 )   This paper presents an analytical formula for estimating the longitudinal wave forces on a large roundended caisson foundation. The establishment of the formula is based on the superposition of the theoretical formula of wave forces on a large circular cylinder and the empirical formula of wave forces on a large rectangular cylinder. With the formula transformed into an inertial force form, a specific inertia coefficient with an exact expression is extracted from the formula. The numerical calculations of the wave forces on round-ended cylinders are carried out by the boundary-element method. The undetermined coefficients in the expression of the inertial coefficient are determined by the numerical results. It is obvious that the numerical values can be well expressed by the computation values from the established formula. By a model experiment carried out in laboratory wave flume, the correctness of the analytical formula is further verified by the measured wave forces on a test model of a round-ended bridge caisson foundation. The comparison shows that the experimental forces can be approximately estimated by this simple calculation method. References | Related Articles | Metrics

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Control Algorithm Using a Revised MIP Method to Deal with Livelocks in S4R of Petri Nets LI Shaoyong* (李绍勇), WU Zongli (吴宗礼), LI Hailin (李海林), WEI Xianhong (魏先宏), CAI Ying (蔡颖), HOU Caiqin (厚彩琴) 2019, 24 (2):  190-195.  doi: 10.1007/s12204-018-2014-x Abstract ( 389 )   PDF (277KB) ( 111 )   Livelocks, like deadlocks, can result in serious results in running process of flexible manufacturing systems (FMSs). Current deadlock control policies (DCPs) based on mixed integer programming (MIP) cannot detect siphons that cause and cope with livelocks in Petri nets. This study proposes a revised mixed integer programming (RMIP) method to directly solve the new smart siphons (NSSs) associated with livelocks in a system of sequential systems with shared resources (S4R), a typical subclass of generalized Petri net models. Accordingly, the solved NSSs are max’-controlled by adding the corresponding control places (CPs). As a result, an original S4R system with livelocks can be converted into the live controlled Petri net system. The related theoretical analysis and an example are given to demonstrate the proposed RMIP and the corresponding control algorithm (CA). References | Related Articles | Metrics

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Elastoplastic Model for Soils Considering Structure and Overconsolidation ZHANG Shuo (张硕), LIAO Chencong* (廖晨聪), ZHANG Qi (张琪), ZHEN Liang (甄亮) 2019, 24 (2):  196-203.  doi: 10.1007/s12204-019-2050-1 Abstract ( 386 )   PDF (865KB) ( 107 )   An isotropic hardening elastoplastic model for soil is presented, which takes into consideration the influence of structure and overconsolidation on strength and deformation of clays. Based on the superloading concept and subloading concept, the inner structural variable ω and overconsolidation variable ρ are introduced to describe the structure and overconsolidation of soil. The present model requires three additional parameters which can be obtained by conventional triaxial test, and the other parameters are same as those of modified Cam-clay (MCC) model. The performance of the proposed model is verified by undrained and drained triaxial tests. References | Related Articles | Metrics

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Infrared Image Reconstruction Based on Archimedes Spiral Measurement Matrix JIANG Yilin* (蒋伊琳), WANG Haiyan (王海艳), SHAO Ran (邵然), ZHANG Jianfeng (张建峰) 2019, 24 (2):  204-208.  doi: 10.1007/s12204-018-2011-0 Abstract ( 429 )   PDF (583KB) ( 110 )   It is a new research direction to realize infrared (IR) image reconstruction using compressed sensing (CS) theory. In the field of CS, the construction of measurement matrix is very principal. At present, the types of measurement matrices are mainly random and deterministic. The random measurement matrix can well satisfy the property of measurement matrix, but needs a large amount of storage space and has an inconvenient in hardware implementation. Therefore, a deterministic measurement matrix construction method is proposed for IR image reconstruction in this paper. Firstly, a series of points are collected on Archimedes spiral to construct a definite sequence; then the initial measurement matrix is constructed; finally, the deterministic measurement matrix is obtained according to the required sampling rate. Simulation results show that the IR image could be reconstructed by the measured values obtained through the proposed measurement matrix. Moreover, the proposed measurement matrix has better reconstruction performance compared with the Gaussian and Bernoulli random measurement matrices. References | Related Articles | Metrics

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Improved Social Emotion Optimization Algorithm for Short-Term Traffic Flow Forecasting Based on Back-Propagation Neural Network ZHANG Jun* (张军), ZHAO Shenwei (赵申卫), WANG Yuanqiang (王远强), ZHU Xinshan (朱新山) 2019, 24 (2):  209-219.  doi: 10.1007/s12204-019-2055-9 Abstract ( 433 )   PDF (454KB) ( 100 )   The back-propagation neural network (BPNN) is a well-known multi-layer feed-forward neural network which is trained by the error reverse propagation algorithm. It is very suitable for the complex of short-term traffic flow forecasting; however, BPNN is easy to fall into local optimum and slow convergence. In order to overcome these deficiencies, a new approach called social emotion optimization algorithm (SEOA) is proposed in this paper to optimize the linked weights and thresholds of BPNN. Each individual in SEOA represents a BPNN. The availability of the proposed forecasting models is proved with the actual traffic flow data of the 2nd Ring Road of Beijing. Experiment of results show that the forecasting accuracy of SEOA is improved obviously as compared with the accuracy of particle swarm optimization back-propagation (PSOBP) and simulated annealing particle swarm optimization back-propagation (SAPSOBP) models. Furthermore, since SEOA does not respond to the negative feedback information, Metropolis rule is proposed to give consideration to both positive and negative feedback information and diversify the adjustment methods. The modified BPNN model, in comparison with social emotion optimization back-propagation (SEOBP) model, is more advantageous to search the global optimal solution. The accuracy of Metropolis rule social emotion optimization back-propagation (MRSEOBP) model is improved about 19.54% as compared with that of SEOBP model in predicting the dramatically changing data. References | Related Articles | Metrics

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Automatic Identification of Butterfly Species Based on Gray-Level Co-occurrence Matrix Features of Image Block XUE Ankang (薛安康), LI Fan* (李凡), XIONG Yin (熊吟) 2019, 24 (2):  220-225.  doi: 10.1007/s12204-018-2013-y Abstract ( 480 )   PDF (2386KB) ( 100 )   In recent years, automatic identification of butterfly species arouses more and more attention in different areas. Because most of their larvae are pests, this research is not only meaningful for the popularization of science but also important to the agricultural production and the environment. Texture as a notable feature is widely used in digital image recognition technology; for describing the texture, an extremely effective method, graylevel co-occurrence matrix (GLCM), has been proposed and used in automatic identification systems. However, according to most of the existing works, GLCM is computed by the whole image, which likely misses some important features in local areas. To solve this problem, this paper presents a new method based on the GLCM features extruded from three image blocks, and a weight-based k-nearest neighbor (KNN) search algorithm used for classifier design. With this method, a butterfly classification system works on ten butterfly species which are hard to identify by shape features. The final identification accuracy is 98%. References | Related Articles | Metrics

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Deformable Registration of Chest Radiographs Using B-spline Based Method with Modified Residual Complexity XIANG Zhikang (相志康), LI Min* (李敏), XIAO Liang (肖亮), LIAN Zhichao (练智超), WEI Zhihui (韦志辉) 2019, 24 (2):  226-232.  doi: 10.1007/s12204-019-2056-8 Abstract ( 468 )   PDF (10184KB) ( 118 )   Accurate registration of chest radiographs plays an increasingly important role in medical applications. However, most current intensity-based registration methods rely on the assumption of intensity conservation that is not suitable for alignment of chest radiographs. In this study, we propose a novel algorithm to match chest radiographs, for which the conventional residual complexity (RC) is modified as the similarity measure and the cubic B-spline transformation is adopted for displacement estimation. The modified similarity measure is allowed to incorporate the neighborhood influence into variation of intensity in a justified manner of the weight, while the transformation is implemented with a registration framework of pyramid structure. The results show that the proposed algorithm is more accurate in registration of chest radiographs, compared with some widely used methods such as the sum-of-squared-differences (SSD), correlation coefficient (CC) and mutual information (MI) algorithms, as well as the conventional RC approaches. References | Related Articles | Metrics

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Research on a Task Planning Method for Multi-Ship Cooperative Driving CHEN Yaojie* (陈姚节), XIANG Shanshan (项珊珊), CHEN Feixiang (陈飞翔) 2019, 24 (2):  233-242.  doi: 10.1007/s12204-019-2057-7 Abstract ( 375 )   PDF (837KB) ( 116 )   A new method for a cooperative multi-task allocation problem (CMTAP) is proposed in this paper, taking into account the multi-ship, multi-target, multi-task and multi-constraint characteristics in a multi-ship cooperative driving (MCD) system. On the basis of the general CMTAP model, an MCD task assignment model is established. Furthermore, a genetic ant colony hybrid algorithm (GACHA) is proposed for this model using constraints, including timing constraints, multi-ship collaboration constraints and ship capacity constraints. This algorithm uses a genetic algorithm (GA) based on a task sequence, while the crossover and mutation operators are based on similar tasks. In order to reduce the dependence of the GA on the initial population, an ant colony algorithm (ACA) is used to produce the initial population. In order to meet the environmental constraints of ship navigation, the results of the task allocation and path planning are combined to generate an MCD task planning scheme. The results of a simulated experiment using simulated data show that the proposed method can make the assignment more optimized on the basis of satisfying the task assignment constraints and the ship navigation environment constraints. Moreover, the experimental results using real data also indicate that the proposed method can find the optimal solution rapidly, and thus improve the task allocation efficiency. References | Related Articles | Metrics

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Research on Two Main Construction Methods of Concept Lattices DONG Ying* (董颖), WU Yue (吴悦), LIU Zongtian (刘宗田) 2019, 24 (2):  243-253.  doi: 10.1007/s12204-019-2058-6 Abstract ( 278 )   PDF (261KB) ( 105 )   Because of the completeness of concept lattices, the time complexity of constructing concept lattices has become the main factor affecting the application of formal concept analysis (FCA). The key problems in the research of concept lattices are how to improve the generation efficiency and how to reduce the space and time complexity of constructing concept lattices. So far, reviews on lattice construction algorithms have not been comprehensive. In view of this situation, we give a detailed review on two categories of construction algorithms: batch methods and incremental methods. The first category is a formal context that cannot be updated once the concept lattice has been constructed; the second category is a formal context that can be updated after a new object being added to the formal context. We briefly introduce classical and improved construction methods, illustrate the deficiencies of some algorithms and point out the improvements of the follow-up algorithms. Furthermore, we compare and discuss several key algorithms, and also pay attention to the application of concept lattices. Finally, two further research directions of concept lattices are proposed, including parallel construction methods of concept lattices and research of heterogeneous data concept lattices. References | Related Articles | Metrics

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Static Lateral Pressure of Heavy Haul Wagon’s End Wall and Side Wall Based on Soil Mechanics WANG Jing* (王婧), ZHANG Qichang (张琪昌), HAN Mingjiang (韩明江), CHEN Tao (陈涛) 2019, 24 (2):  254-261.  doi: 10.1007/s12204-019-2059-5 Abstract ( 368 )   PDF (327KB) ( 101 )   A new analytical method for calculating the static lateral pressure is introduced to obtain more accurate calculation method of the lateral pressure of end wall and side wall of heavy haul wagon. In the method, the influence of mechanical characteristics of the end wall is considered. For the end wall, a basis for lightweight design can be provided by deducing an analytical method of the lateral pressure which is closer to the experimental results. For the side wall, calculation formula which takes the cycloid curve as projection of rupture surface is derived. The correctness of the formula is verified by comparison with the experimental results. The nonlinear distribution of lateral pressure along the height direction is achieved. Further research is done on the relationship between key parameters of the heavy haul wagon design and the lateral pressure on the side wall. References | Related Articles | Metrics

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Optimization of Clinching Tools by Integrated Finite Element Model and Genetic Algorithm Approach WANG Menghan* (王梦寒), XIAO Guiqian (肖贵乾), WANG Jinqiang (王晋强), LI Zhi (李志) 2019, 24 (2):  262-272.  doi: 10.1007/s12204-018-1995-9 Abstract ( 409 )   PDF (3852KB) ( 113 )   Clinching is a convenient and efficient cold forming process that can join two sheets without any additional part. This study establishes an intelligent system for optimizing the clinched joint. Firstly, a mathematical model which introduces the ductile damage constraint to prevent cracking during clinching process is proposed. Meanwhile, an optimization methodology and its corresponding computer program are developed by integrated finite element model (FEM) and genetic algorithm (GA) approach. Secondly, Al6061-T4 alloy sheets with a thickness of 1.4mm are used to verify this optimization system. The optimization program automatically acquires the largest axial strength which is approximately equal to 872N. Finally, sensitivity analysis is implemented, in which the influence of geometrical parameters of clinching tools on final joint strength is analyzed. The sensitivity analysis indicates the main parameters to influence joint strength, which is essential from an industrial point of view. References | Related Articles | Metrics