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30 June 2018, Volume 39 Issue 3 Previous Issue    Next Issue

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Adaptive Sampling Method for Solid Wall Virtual Particle Boundary Handling in SPH Fluid Solid Coupling Simulation ZHU Xiaolin, WANG Huanhuan, YIN Jingcun 2018, 39(3): 381-388.  DOI: 10.11996/JG.j.2095-302X.2018030381 Abstract ( 98 )   PDF (8497KB) ( 117 )   The method for solid wall virtual particle boundary handling is a main boundary handling method in fluid simulation, while it cannot ensure that no fluid penetrates the solid boundary, and requires a huge amount of computation. To prevent fluid particles from penetrating the boundary, in this paper a damp zone is set up near the boundary, and each fluid particle in this zone will be applied by the boundary with an elastic force and a damping force that is opposite to the moving velocity of the fluid particle. Therefore, the particles near the boundary become more stabilized. To reduce the amount of computation, this paper proposes two adaptive sampling methods for boundary particles based on different numbers of particles around the boundary: one is to adaptively sample particles of different masses; the other is to adaptively sample particles of the same mass in different layers. Compared with the traditional method for solid boundary particle sampling, these two adaptive sampling methods reduce the number of boundary particles, accelerate the simulation speed and save the computer memory. In addition, all of the 3D fluid simulations in this paper are based on the GPU acceleration technique, and can interact in real time. Related Articles | Metrics

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Point Cloud Registration Algorithm Based on Local Features ZHAO Fuqun1,2, ZHOU Mingquan2,3, GENG Guohua2 2018, 39(3): 389-394.  DOI: 10.11996/JG.j.2095-302X.2018030389 Abstract ( 97 )   PDF (500KB) ( 200 )   Aiming at low-coverage-rate point clouds, a registration algorithm was proposed based on local features in the paper. Firstly, local features including the local depth, deviation angle between normals and point cloud density are extracted, and the local feature descriptor is obtained. Secondly, the correspondence of local feature sets is calculated and the corresponding candidates are gained. Thirdly, the outliers are eliminated and coarse registration is achieved. Lastly, an improved iterative closest point (ICP) algorithm based on the rotation angle constraint, and the dynamic iterative coefficient is employed to complete fine point cloud registration. The experiment results reveal that the point cloud registration algorithm could achieve the precise registration of low-coverage-rate point cloud, based on local features, a high-precision and fast one. Related Articles | Metrics

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A Progressive Interpolation Scheme for Loop Subdivision Surfaces with Shape Adjustment CHEN Tiantian, YAN Di, WANG Wei, ZHAO Gang 2018, 39(3): 395-401.  DOI: 10.11996/JG.j.2095-302X.2018030395 Abstract ( 62 )   PDF (1224KB) ( 135 )   Aming at the problems that Loop subdivision can’t satisfy the shape adjustment and interpolate the given mesh, a progressive interpolation scheme for Loop subdivision surfaces with shape adjustment is presented. Firstly, an equivalent Loop subdivision mask that can adjust the mesh vertices uniformly and facilitate the introduction of weight to adjust the shape of subdivision surfaces is proposed. Secondly, the new grid is generated by the iterative adjustment of the initial control grid, and using the two-phase Loop subdivision scheme presented in this paper to subdivide the new mesh, the shape-adjustable Loop subdivision surface that interpolate the initial control vertices is obtained. Finally, the convergence of the scheme is proved and some typical examples are illustrated to verify its effectiveness. Related Articles | Metrics

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Double-Parameter Geometric Subdivision Method MENG Huining1, LI Yajuan1, XU Huixia2, LIU Jianzhen1, DENG Chongyang 1 2018, 39(3): 402-410.  DOI: 10.11996/JG.j.2095-302X.2018030402 Abstract ( 50 )   PDF (1778KB) ( 147 )   A geometric subdivision method based on double parameters is proposed in this paper. Firstly, the new control points are determined by the original control points and their tangents: using the quadratic rational Bézier curves formula in which the parameter t is 0.5, let two adjacent points and the intersecting point of their tangents be the control points of Bézier curves, and take its weight as the first parameter  to calculate new points. Then we calculate new tangent vectors of all points: after define provisional tangent vectors, the circle-tangent of this point is computed by the point and its two adjacent points; whereafter define the formula of new tangents for all points by introducing the second parameter  related to tangent vectors. Theoretical analyses show its convexity preserving and convergence. If the second parameter =0, and next step we define a new factor by the initial parameter , its limit curve is a piecewise rational quadratic C1 curve. The circle preserving of this scheme can be obtained by computing new points with different parameters  in every step under =1. The effectiveness of this approach is verified by some numerical examples. Related Articles | Metrics

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SPH-Based Simulation of Raindrops Beating an Irregular Boundary LIU Jiarui1, YANG Meng1, WU Jiaze2, YANG Gang1 2018, 39(3): 411-418.  DOI: 10.11996/JG.j.2095-302X.2018030411 Abstract ( 79 )   PDF (1213KB) ( 138 )   In order to simulate the process of raindrops hitting branches and other irregular boundary, research has been conducted on the force of the fluid particles on solid boundaries represented by the grid. A kind of boundary force simulation method without particle sampling is proposed. This approach exploits the Gauss quadrature rules to integrate the triangular patches of a mesh model and correct the particle density on the solid-liquid boundary. In addition, several parameters, including pressure and viscous forces on the solid-liquid boundary, are also calculated using an integral method to ensure the continuity of the boundary force and avoid a splashing phenomenon at the moment of particles’ beating the boundary. Meanwhile, this paper propounds an attractive force model to control the movement of the boundary particles flowing down on the surface of an object. The experimental results reveal that the approaches proposed in this paper can achieve more realistic effects of phenomenon simulations, such as the raindrop spreading, retracting and flowing along the boundary, etc. Related Articles | Metrics

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Automatic Filling Algorithm of Arbitrary Complex Region Based on Grid QIU Guoqing 2018, 39(3): 419-423.  DOI: 10.11996/JG.j.2095-302X.2018030419 Abstract ( 63 )   PDF (600KB) ( 135 )   A fully automated filling algorithm for any complex area is designed based on the principle of grid and equal-spaced parallel lines. Firstly, we turn the whole area filling into grid. Secondly, we draw a series of equidistant parallel lines and calculate row column ordinal value of each parallel line going through the polygon grid. Thirdly, each grid cell is filled with the autonomous cycle method, according to the calculation of the row and column number value of the grid. Finally, the entire area is automatically filled. The verification of multiple sets of data through an independently designed application program indicates that the algorithm can realize filling quickly and automatically, and a detailed analysis is made on the technical difficulties that occur in the experiment. Related Articles | Metrics

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Vertex Invariants Based on Level-Order Traversal and Their Graph Invariants JIANG Shunliang, TANG Yiling, GE Yun, XU Shaoping, YE Famao 2018, 39(3): 424-431.  DOI: 10.11996/JG.j.2095-302X.2018030424 Abstract ( 85 )   PDF (507KB) ( 125 )   In order to find graph invariants with higher performance, fifteen kinds of vertex invariants are defined by weighted accumulation with the help of vertex data in the process of level-order traversal. Every kind of vertex invariants are able to compose a graph invariant after being sorted. The vertex degree is divided into the internal degree, the forward degree, and the backward degree during the traversal, while the internal degree and the backward degree include the number of loops. Three kinds of vertex invariants are selected based on the refining performance, and then the graph invariants are generated. The combination of three kinds of graph invariants performs well in distinguishing a variety of non-isomorphic connected graphs. Not only all the non-isomorphic graphs with the number of vertexes N≤8 are distinguishable, but also the number of undistinguishable graphs with N=9 is reduced from 989 of literature [9] down to 40, with the degeneracies of these graph invariants approaching 2. Random tests shows that these graph invariants have good performances in differentiation. Related Articles | Metrics

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Wheel Tread Area Extraction Based on Image Distortion Correction WANG Yongsheng, MA Zengqiang, SONG Zibin, XIAO Meiling 2018, 39(3): 432-439.  DOI: 10.11996/JG.j.2095-302X.2018030432 Abstract ( 56 )   PDF (4238KB) ( 223 )   In order to realize accurate measurement of the area of tread defect, a new method of wheel tread area extraction is proposed based on image distortion correction. Firstly, the improved colorful image labeling watershed algorithm is adopted to segment the surface image of the side view. Then, the geometric correction is perfomed according to different characteristics of the horizontal and vertical distortion of tread surface image. In this process, the two segmentations and the perspective transformation of tread area are completed. Finally, a correction image is obtained from the tread angle. The experimental results reveal that this method can accurately segment and correct the side view of the tread image, which lays a solid foundation for the accurate calculation of tread defect area. Related Articles | Metrics

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On the Surface Damage Features of Transmission Line Conductors Based on Image Processing ZHANG Xinchun, CAO Yingping, HAN Chunyu, BAI Yuncan 2018, 39(3): 440-447.  DOI: 10.11996/JG.j.2095-302X.2018030440 Abstract ( 78 )   PDF (9628KB) ( 136 )   The surface damage of conductors is an important factor in affecting the mechanical and electrical performances of overhead transmission lines. Thus, it is important to study the surface damage features of conductors for the durability design and safety assessment of transmission conductors. Firstly, several typical conductors (aluminium conductor steel reinforced, ACSR) in different regions and voltage levels are selected as the objects of study in this paper. Then the image information of the damaged surface of conductors is extracted by image processing technology. An improved pixel covering algorithm is proposed to make up for the shortcomings of the traditional pixel covering method, and thus the relations between surface damage features and fractal dimensions of conductors can be established. Research results show that there is obvious fractal rule in the conductor surface topography. The fractal dimensions can measure the surface damage characteristics of conductors. The two-dimensional (2D) fractal dimension tends to become smaller with the decrease in the conductor surface damage. The increase in the unevenness of conductor surface will improve the 3D fractal dimensions. When the damage of the conductor surface is a scar, the 2D fractal dimension is between 1.5 and 1.7. If the damage is characterized with wear, the fractal dimension spans from 1.2 to 1.4; whereas the damage is characterized with corrosion, the fractal dimension ranges from 1.4 to 1.5. Related Articles | Metrics

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An Improved Optical Flow Algorithm for Micro Expression Detection in the Video Sequence LI Qiuyu1, ZHANG Yuming2, YANG Fumeng3, ZHAN Shu1 2018, 39(3): 448-452.  DOI: 10.11996/JG.j.2095-302X.2018030448 Abstract ( 55 )   PDF (719KB) ( 140 )   Micro-expression is a kind of short-duration subtle expression which is not controlled by the autonomic nervous system. Micro-expression appears when a person is attempting to conceal his true emotion. Micro-expression detection boasts great application prospects in many fields, such as public security, investigation and interrogation as well as clinical medicine due to its close relationship with lie detection. Automatic detection of micro-expressions has come to the fore in research, because it is of great difficulty to artificially identify micro-expression . This paper proposes an improved algorithm based on the Horn-Schunck (HS) optical flow for automatic micro-expression detection. In this study, the pre-conditioned Gauss-Seidel iterative method is employed to improve the HS optical flow method, which accelerates the convergence rate. Experiments in the spontaneous micro-expression database CASME show that the propounded method exerts an excellent effect on the detection of micro-expression. Related Articles | Metrics

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Underwater Image Enhancement Based on the Principle of Dark Channel Prior ZHU Zhenjie1, WANG Hongru1,2 2018, 39(3): 453-462.  DOI: 10.11996/JG.j.2095-302X.2018030453 Abstract ( 146 )   PDF (2404KB) ( 260 )   In view of the serious degradation of the underwater images caused by underwater light attenuation and scattering, a new method of underwater image enhancement is proposed in this paper. The new method based on the principle of dark channel prior conducts underwater image enhancement and image thinning on dark channel by the method of soft matting. In the first 0.1% brightest pixels of the image, the medians of these pixels are calculated through the median filtering algorithm. Then, the differences between these pixels and their corresponding medians are calculated, and the pixel of minimum difference is employed as an estimate of the background light. The accuracy of the estimated background light is judged by the color saturation variance of the region around the pixel. Afterwards, the Retinex algorithm and the ratio of attenuation coefficients for each color channel are adopted to conduct color correcting for enhancement images. It is shown by experiments that the proposed method can effectively dehaze the underwater images, correct the color cast of images and further enhance the image contrast. Related Articles | Metrics

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Optimization and Behavior Identification of Keyframes in Human Action Video ZHAO Hong, XUAN Shibin 2018, 39(3): 463-469.  DOI: 10.11996/JG.j.2095-302X.2018030463 Abstract ( 139 )   PDF (515KB) ( 175 )   In the course of behavior identification, extracting keyframes from the video can effectively reduce the amount of video index data, so as to improve the accuracy and real-time performance of behavior identification. A method for optimizing the keyframe sequence is proposed to improve the representativeness of keyframes, on which the behavior identification is based. Firstly, the K-means clustering algorithm is employed to extract keyframes in the human action video sequence according to 3D human skeleton features. Then, the quadratic optimization is performed in the light of the location of keyframes to extract the optimal keyframe, and it can reduce the redundancy of keyframe sequence, compared with traditional ways. Finally, the behavior video is identified by convolutional neural network (CNN) classifiers in accordance with the optimal keyframe. The experiment results on the Florence 3D Action dataset indicate that the method has a high identification rate, and drastically shortens the identification time, compared with the traditional method. Related Articles | Metrics

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Symmetry Invariance Shape Context Feature Extraction and Image Matching JIA Gengyun, ZHAO Haiying, ZHOU Qian, LI Xueming 2018, 39(3): 470-476.  DOI: 10.11996/JG.j.2095-302X.2018030470 Abstract ( 53 )   PDF (1625KB) ( 224 )   Shape context is a popular algorithm of image shape feature extraction and matching, traditional shape context algorithm lacks symmetry invariance, which means it can not match two similar but symmetrical shapes. To overcome this shortcoming, this article proposed an improved shape context algorithm with symmetry invariance. The method defines the gradient direction of a sample point as its 0 rad in log polar coordinates when computing the angle relations in shape context, then compare the number of sample points in 0 rad to π rad and π rad to 2π rad, and adjust the angel increasing direction in the coordinate according to the results. In the process of iterative shape warping and shape contexts calculation, the symmetry invariance descriptors are only applied in the first iteration to obtain a more stable matching result. Experimental results show that the proposed algorithm can effectively establish match between two similar and symmetrical shapes, and therefor improve the retrieval precision. Related Articles | Metrics

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Apply Vehicle Vision to Detect Driver’s Rearview Mirror Watching Behaviors HUANG Bo1, ZHONG Mingen1,2, WU Pingdong3, HUANG Jiehong1, QIAO Yunhao1 2018, 39(3): 477-484.  DOI: 10.11996/JG.j.2095-302X.2018030477 Abstract ( 46 )   PDF (4006KB) ( 300 )   The driver’s rearview mirror watching behavior is one of the necessary steps for driving safety when the vehicle is turning, however, the detection technology or application of this behavior is still absent. Thus an adaptive detection method of the drivers’ rearview mirror watching behaviors during the vehicle steering process was presented in this paper with the help of vehicle vision and image process technology for safety monitoring and reminding. A frame spatial gradient differences searching algorithm was designed to complete the initial parameters’ learning work on both the drivers’ face and neck regions when the vehicle engine was fired, while a expand-contract searching algorithm was invented to accomplish a fast recognition when the vehicle was moving. Contours of the driver's face and neck parts were extracted without segmentation. An area ration between left and right parts of the contours separated by a vertical line passing through the base point of neck contour was defined as a characteristic parameter. By analyzing the drivers’ eye movement data during driving, a discipline called local peak value distributing of the parameter’s cumulative probability was uncovered, which helped to build a real time eigenvalue reference estimation method and a threshold judging principle of the drivers’ rearview mirror watching behaviors. Experimental results showed that this method was not sensitive to the types and details of drivers' faces, and was robust to some disturbance, and the overall detection accuracy rate was 96.1%. Related Articles | Metrics

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Multitask Fine-Grained Vehicle Identification Based on Deep Convolutional Neural Networks WANG Haiyao1, TANG Juan2, SHEN Zhenhui1 2018, 39(3): 485-492.  DOI: 10.11996/JG.j.2095-302X.2018030485 Abstract ( 120 )   PDF (1735KB) ( 292 )   Vehicle identification, especially fine-grained vehicle identification, is an important part of modern intelligent transportation system. Aiming at the problem that it is difficult to effectively recognize fine-grained vehicle using traditional vehicle identification methods, we take three classic deep convolutional neural networks (such as AlexNet, GoogleNet and ResNet) as the basic networks, and introduce the classification of vehicle types as the auxiliary task, together with fine-grained vehicle identification task to constitute a multitask joint-learning model. By training and evaluating our model on a public data set which contains 281 vehicle types, we have demonstrated the excellent performance of this model in fine-grained vehicle identification task with no need of annotations about vehicle parts’ location and additional 3D information. Besides, with the introduction of multitask learning strategy, the performance of this model can be improved, compared with that of any single-task learning model. Our model is simple and efficient, and can basically meet the demand of practical applications. Related Articles | Metrics

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Research on Apple Picking System Based on Visual Identification and Location LI Zhenyu, WANG Haochen 2018, 39(3): 493-500.  DOI: 10.11996/JG.j.2095-302X.2018030493 Abstract ( 72 )   PDF (2352KB) ( 298 )   The task of apple picking robot become more complicated for swing and overlapping of apple. Thus the paper proposes a new apple picking method based on visual identification and location technology. It can help robot to find out target more efficiently by visual inspection technology in the Orchard. Firstly, we applied image filtering, histogram equalization and image segmentation to make the background and fruit’s contour separated. Secondly, the proposed algorithm applied to calculate the curvature of edge contour to find the peak point of curvature. Finally, this study converted the pixel coordinate of peak point calibrated, and turning pixel coordinate into world coordinate system to make it the target point for robot which robot can grab. Robot could adjust posture to trace fruit and identify it with position information of target point, and then find it, grab it, and pick it accurately. The experiment showed the robot grab the fruits of success rate as high as ninety percent above by applying proposed method. The proposed study also provide some valuable reference for identify and locating of spherical or round shaped fruits. Related Articles | Metrics

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An Adaptive Feature Extraction Method Based on PCA ZHANG Xin, DIAO Luhong, NAN Dong, WANG Yongli, LIU Yang 2018, 39(3): 501-508.  DOI: 10.11996/JG.j.2095-302X.2018030501 Abstract ( 63 )   PDF (919KB) ( 130 )   An adaptive features extraction method is proposed. It defines an adaptive objective function based on the projective space derived by using PCA method. Then the projection space of the individual sample is computed. The distribution characteristics of each sample are well considered. In order to make the algorithm applicable to the classification problem, a similarity measurement is proposed to calculate the similarity between individual samples in different projection spaces. Compared with the Euclidean metric, the proposed measurement is proved that can represent the geodesic distance relationship between the samples better, so that the proposed method can learn the manifold data effectually. The classification and reconstruction experiments on the different databases indicate that the new method can obtain features more effectively and robustly. Related Articles | Metrics

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Study on the Technologies of Close Range Photogrammetry and Applications in the Manufacture of Aviation ZHAO Boya1, ZHANG Chengyang2, JING Xishuang2 2018, 39(3): 509-514.  DOI: 10.11996/JG.j.2095-302X.2018030509 Abstract ( 48 )   PDF (1463KB) ( 126 )   In recent years, the technologies of close range photogrammetry have been widely used in the manufacture of aviation, so the technologies of close range photogrammetry and applications are studied. This article describes the composition of a close range measurement system and the close range measuring equipment produced by companies at home and abroad. The taking of measurement points and the calibration of close range photogrammetry are discussed. The advantages and disadvantages of close range photogrammetry are summarized. The applications of close range photogrammetry in the manufacture of aviation are described. Related Articles | Metrics

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Experience Measurement of Three Navigation Interfaces in Virtual Riding JIANG Lijun1,2, LI Jianyu1, LI Zhelin1,2, WU Zhanghong1, ZHANG Yu1 2018, 39(3): 515-521.  DOI: 10.11996/JG.j.2095-302X.2018030515 Abstract ( 105 )   PDF (3348KB) ( 130 )   Relevant researches indicate that most users meet difficulties in navigation in virtual reality. However, the current study on navigation is still insufficient. Aiming at this problem, a study on immersive virtual riding is conducted to measure the user experience of different navigational interfaces including the map, the directional icon and the light path. The evaluation indicators involve efficiency, satisfaction and learnability. Subjects will ride along the paths in virtual environment to reach the destination and the system will record the riding time and the number of collisions to quantify different elements of user experience. The experimental result shows as follows. Firstly, the directional icon can increase the efficiency of virtual riding to some, but not significant degree. However, the directional icon contributes to low perception of other objects in virtual environment. Secondly, when the users use light path to navigate, the usability and the learnability are significantly improved. Lastly, there is little difference between the experience of map navigation and the experience without any navigation. Related Articles | Metrics

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Research on IFC-Based Storage and Application of Sensor Information HU Zhenzhong1, TIAN Peilong1, LI Jiulin2 2018, 39(3): 522-529.  DOI: 10.11996/JG.j.2095-302X.2018030522 Abstract ( 86 )   PDF (3266KB) ( 140 )   There are a lot of sensor data collected in the construction, operation and maintenance of buildings, but these data only existed in the respective monitoring systems, leading to a situation of “information island”, thus the sensor data cannot be effectively used. BIM (building information model/modeling) technology can implement integrated management and application of sensor data and engineering data. The IFC (industrial foundation classes) standard which is an international standard for BIM storage, is still not sufficient for sensors and their data. In this paper, IFC-based sensor information storage method and application process are presented. Specifically, the description and association mechanism of sensor information in IFC are analyzed, followed by the extension of IFC property set to achieve the storage of such information. Finally, the IFC-based application process of sensor information is described. The proposed methods were applied to the HuaiFang Water Reclamation Plant in Beijing for validation. Related Articles | Metrics

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IFC and gbXML Based Test and Evaluation for the Interoperability Between BIM Modeling Software and Green Building Performance Analysis Software CHEN Yuan, KANG Hong, FAN Yunchang 2018, 39(3): 530-537.  DOI: 10.11996/JG.j.2095-302X.2018030530 Abstract ( 106 )   PDF (2318KB) ( 139 )   Green building and building energy conservation are important factors in the sustainable development of the construction industry. However, BIM (building information modeling) has a wide range of software and various data standards, and loss of information is frequent during the data transfer. Thus solving the “information island” problem and the interoperability issues between different software is the key for BIM application. This paper first analyzes the green building framework based on IFC (industrial foundation classes) and gbXML standards, and chooses BIM modeling software ArchiCAD and green building performance analysis software Ecotec to test and evaluate the interoperability, so as to identify the problems of BIM data standards and BIM tools in the process of BIM data transfer. The paper provides specific improvement methods and suggestions to solve the problems, including reducing the information redundancy for IFC formats, increasing the support to green building area in the IFC standard, and improving the accuracy for the definition of green building information in the IFC resource layer. Related Articles | Metrics

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Research on Production Information Model of Prefabricated Components Based on IFC Standard GAO Qiuya1,2, GAO Xinwen1,3 2018, 39(3): 538-546.  DOI: 10.11996/JG.j.2095-302X.2018030538 Abstract ( 56 )   PDF (778KB) ( 146 )   This paper is based on the research of BIM mainstream standard IFC (industrial foundation classes), which has been developing rapidly in recent years. According to the data sharing requirement of prefabricated components, the production information organization and expression mode of prefabricated components are studied. In accordance with the IFC standard, this paper divides the information of the prefabricated components in the production stage into product information, process information, resource information, cost information and site information, and establishes the information model of prefabricated components based on IFC standard. Finally, this paper gives a concrete example of applying the information model of prefabricated components. The result shows that the information model can effectively improve the management of data information and the cooperative production efficiency. Related Articles | Metrics

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Research on Product Imagery Design by Simulating Design Thinking SU Jianning, ZHAO Xinxin, JING Nan, CHEN Yanhao 2018, 39(3): 547-552.  DOI: 10.11996/JG.j.2095-302X.2018030547 Abstract ( 66 )   PDF (791KB) ( 130 )   In order to enhance the efficiency and quality in product imagery design, an auxiliary method of simulating the design thinking process is proposed. Through the experiment on conception of the product imagery, the designer’s design thinking is analyzed. The design activity can be divided into three parts: analyzing proposition, generating creative solution and optimizing creative solution. For the key node strategy, the corresponding simulation model is established using AHP, directed similarity method, approaching ideal solution, neural network, genetic algorithm and so on. Finally, the effectiveness of the method is verified by the design scheme of the retro-styled faucet. Related Articles | Metrics

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On Human-Like Motion Planning Algorithm of Anthropomorphic Mechanical Arms Based on Hierarchical Planning Strategy WANG Chunrong1, XIA Erdong1, ZHAO Jing2, XIONG Changjiong1, LIU Jianjun1, WEI Yuan3 2018, 39(3): 553-561.  DOI: 10.11996/JG.j.2095-302X.2018030553 Abstract ( 63 )   PDF (3732KB) ( 185 )   In order to make anthropomorphic mechanical arms generate human-like movements accurately, a novel human-like motion planning method is proposed, which combines the trigger conditions and hierarchical planning strategy (HPS). The method decomposes the complete arm movements into a set of different motion processes, each of which has corresponding planning hierarchies. The anthropomorphic mechanical arms reveal different characteristics in different planning hierarchies. The motion models and posture prediction indicators in varying planning hierarchies are built based on the respective characteristics to predict the postures of anthropomorphic mechanical arms. The experiment is acted on humanoid robot NAO as the platform, and then the prediction results of static and dynamic arm postures is performed by the proposed method and the minimum total potential energy (MTPE) are compared. In addition, the prediction results are compared with the real arm motion data collected by motion capture system (OptiTrack). The experimental results show that the errors of static and dynamic posture prediction of proposed method could be reduced, and the anthropomorphic mechanical arms can generate the human-like movements accurately through the proposed method. Related Articles | Metrics

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A Sequential Positioning Algorithm for Problem of Circular Parts Coiled Sheet Packing LU Tao1, PAN Weiping2 2018, 39(3): 562-566.  DOI: 10.11996/JG.j.2095-302X.2018030562 Abstract ( 63 )   PDF (282KB) ( 99 )   The problem of circular parts coiled sheet packing means that a set of different radius circular parts are non-overlappingly packed on the coiled sheet with specified width, so that the occupied length of the coiled sheet is minimized. To solve this problem, a sequential positioning heuristic optimization algorithm is proposed. A positioning algorithm is designed based on maximum caving degree. For each particular packing sequence, caving degrees of all feasible placement location of circular parts are calculated, and the location which has the highest caving degree is selected to pack the circular part. The current layout is updated, and the packing of the residual circular parts is continued, according to the above rule until all of circular parts are packed into the coiled sheet. Genetic algorithm is employed to evolve the packing sequence, in order to obtain a great number of different packing schemes, and the packing scheme with the minimum coiled sheet length is chosen as the final solution. The experimental results show that the algorithm scheduling scheme of this paper consumes less coil length, and the calculation time of the algorithm is relatively reasonable. Related Articles | Metrics

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On Layout Optimization Based on Genetic Simulated Annealing Algorithm ZHOU Jiazhi, YIN Ling, ZHANG Sumin 2018, 39(3): 567-572.  DOI: 10.11996/JG.j.2095-302X.2018030567 Abstract ( 69 )   PDF (323KB) ( 151 )   Based on the integration of the genetic algorithm (GA) and the simulated annealing algorithm, an improved lowest horizontal line (ILHL) algorithm is presented in order to improve utilization and stability of the rectangular packing algorithm. In this algorithm, a signed decimal encoding is utilized to generate the gene sequence in accordance with the length-width ratio and the area of the rectangle, which is employed to establish the initial population. The improved lowest horizontal line algorithm adopts the best individuals from a number of random sequences with different nesting orders and layout sizes, uses utilization rate as the fitness function and reduces the idle area. In this paper, a contrast experiment is operated to compare ten groups of rectangular data randomly generated by ILHL with those generated by GA proposed in the current literature. The experiment results show that our algorithm (ILHL) can effectively improve the utilization rate and time efficiency of the packing results. Related Articles | Metrics

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Research on Visual Customization Based on SolidWorks FAN Dejun1,2, WEN Jingsong1,2, XU Yong1,2, SONG Jian1,2 2018, 39(3): 573-578.  DOI: 10.11996/JG.j.2095-302X.2018030573 Abstract ( 60 )   PDF (481KB) ( 130 )   In order to solve the problem of real-time automatic assembly and interactive browsing in visual customization system, an automatic assembly method based on secondary development of SolidWorks in network environment is proposed. User defined customized solutions on the web page and a remote communication between a server and a server that has a fixed connection. The automatic assembly program secondary development of SolidWorks installed on the host. The server automatic assembly program remote boot on the host and receive the complete assembly of eDrawings files. The 3D model is fed back to the web page. The user can browse the web page in the realization of virtual interaction. This method can realize the real time automatic assembly and virtual interaction of the 3D model under the multi choice scheme. Related Articles | Metrics

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Progressive Fractal Facilitation Teaching Method for Composite Solid Dimensioning LIU Yu1, ZHOU Jiawei2 2018, 39(3): 579-586.  DOI: 10.11996/JG.j.2095-302X.2018030579 Abstract ( 46 )   PDF (578KB) ( 141 )   Composite solid dimensioning is of great significance and difficulty in engineering graphics teaching. A progressive fractal facilitation teaching method is proposed based on the coherence of dimensioning and the shape decomposition of composite solid. The fractal facilitation method is employed in each step to decompose the complicated composite solid into simple one, through the progressive teaching method by means of taking into account the similarity of geometric solid. The iteration rule for the fractal facilitation method of dimensioning can be referred to as decomposing, shaping, locating and merging, which is corresponding to steps of decomposing the composite solid, ascertaining the number of shape size, ensuring the number of location size, and merging the repetition sizes. Three principles of dimensioning de-duplication have to be identified, and the fractal facilitation method for dimensioning is applied, in terms of different composite solids. The application of the progressive fractal facilitation method of dimensioning can take full advantage of the similarity of geometric solid, and lead students to accomplish the dimensioning of composite solid gradually, thus attaining a correct and complete dimensioning of composite solid. Related Articles | Metrics

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The Assistant Learning System of Engineering Drawing Based on Mobile Augmented Reality HOU Shouming1,2, LIAN Panpan1, XU Wenpeng1, CHEN Keyao1 2018, 39(3): 587-593.  DOI: 10.11996/JG.j.2095-302X.2018030587 Abstract ( 67 )   PDF (2374KB) ( 146 )   In the course of engineering drawing, it is a great challenge for beginners to conceive three-dimensional shapes on two-dimensional drawings. This paper analyzes the shortages of traditional PC-based multimedia-assisted teaching methods in interactivity and convenience, and proposes an engineering drawing system based on mobile augmented reality. This system adopts the unmarked recognition technology to realize the natural interaction between engineering drawings and three-dimensional digital models, on the basis of which, an assistent learning application with multifunction has been developed. Users can use the cellphone camera to scan and identify the two-dimensional engineering drawings and overlapping display of three-dimensional models, and other teaching resources are also supported on the phone. Users can also zoom in or rotate the models, and disassemble and assemble those complicated assembly models. The result shows that the system is not only convenient for students’ autonomous learning, but also helpful in improving the teaching environment of engineering drawing courses. Related Articles | Metrics

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Innovation Ability Training Oriented Course Project of Engineering Graphics Reformation for Undergraduates ZHANG Zongbo, WANG Min, LIU Yancong, YI Peng, LI Jing, NIU Wenjie 2018, 39(3): 594-598.  DOI: 10.11996/JG.j.2095-302X.2018030594 Abstract ( 62 )   PDF (3956KB) ( 152 )   Training of human resource with high self-renovation capability is concerning with the improvement of the core competitiveness of the nation and the development of advanced manufacturing technology. The most important platforms for self-renovation capability training in our country is higher education. The current situation of course project of engineering graphics is analyzed and the common problems are proposed. According with the teaching practice of our team, the teaching method, the management and examination system of the he project teaching was reformed. All these can help release the contradiction between less teaching hours and more work of drawing. The results proved that it is a beneficial exploration on practical capability and self-renovation capability training for undergraduates. Related Articles | Metrics

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Configuration Design for Assembly of Congruent Geometric Figure Based on Two-Sided Projection MENG Xiangbao, WANG Yankun, DONG Zhengrong 2018, 39(3): 599-604.  DOI: 10.11996/JG.j.2095-302X.2018030599 Abstract ( 95 )   PDF (1836KB) ( 145 )   Projection analysis and configuration design of assembly constitute one of the essential contents in engineering graphics course. It lays foundation for engineers to read technical drawings, and design details of geometric structures of machine parts. For this purpose, a series of example are shown based on isosceles triangles, isosceles right triangles, squares, circles, and combinations of squares as two-sided projection. And spatial divergence conception is worked out by means of line-surface and shape-volume analysis of basic units as prism, pyramid, cylinder, cone, sphere and torus. In result, assembly of various geometric shapes and the third projection are derived. 3D geometric models are implemented using CATIA software. It strengthens the ability of spatial ideation, provides fundamental samples for geometric configuration design, and enhances logicality and interestingness in the process of projection analysis. Related Articles | Metrics

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Thought on the Teaching Reformation of the Engineering Drawing Combined with the Internet Plus Based on the Massive Open Online Course WANG Xiaofei1,2, MU Haozhi1,2, XUE Lijun1,2, NIU Xinghua3 2018, 39(3): 605-609.  DOI: 10.11996/JG.j.2095-302X.2018030605 Abstract ( 72 )   PDF (1431KB) ( 215 )   With the progress of the times, people can acquire information at any time and any place. The massive open online course (MOOC), a novel teaching method, can present knowledge in real time and multidimensional mode. MOOC idea conforms to the information times, and accords with the thinking characteristics and personality traits of contemporary students. Considering the present situation in higher education, we can change the traditional teaching method that is employed on the engineering drawing course in the university by integrating MOOC idea therein. The thinking on the teaching reformation of engineering drawing course based on MOOC idea is presented in this paper. In the teaching process of the engineering drawing course, it is necessary to make full use of the internet advantages. The practice of classroom teaching combined with internet plus makes continuous progress in engineering drawing teaching. Our practices show that the new teaching style “internet plus” for the engineering drawing course can expand teaching time and space, and is well welcomed by all students. Related Articles | Metrics