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31 December 2015, Volume 36 Issue 6 Previous Issue    Next Issue

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On Graphics Textbook He Yuanjun, Wang Ziru 2015, 36(6): 819-827.  DOI: 10.11996/JG.j.2095-302X.2015060819 Abstract ( 109 )   PDF (327KB) ( 259 )   Within the concept of Great Graphics, this paper discusses about graphics textbooks and graphics teaching. From the perspective of the discipline classification, scientific foundation of graphics, computing foundation, the practice of graphics, and graphic application, some issues about theoretical and practical teaching of graphics are discussed. Based on the concept that shapes are source of graphs and graphs are the manifestation of shapes, some principles of main graphics textbooks including engineering graphics, descriptive geometry, computer graphics and computer image are given. As the essence of graphs is geometry, this paper finally suggests to compile Graphic Computing Foundation as the public graphics textbook. Related Articles | Metrics

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Research on the Development and Application of a New Teaching Aid#br# Based on Descriptive Geometry Teaching Chen Guang, Du Wei, Liu Xiaodong, Han Si 2015, 36(6): 828-833.  DOI: 10.11996/JG.j.2095-302X.2015060828 Abstract ( 105 )   PDF (14791KB) ( 97 )   For the visual demonstration teaching aids in descriptive geometry develop slowly, a new comprehensive demonstration teaching aid is developed by using rotating mechanism, slider-guide institutions, double slider-rocker mechanism and the single chip microcomputer control. It implements the integration operation demonstration such as the show of projection features and typical examples in the descriptive geometry. By solving the problems of the line, line-surface and method of conversion surface, it has carried on the shows of specific examples. The shows provide the application of this teaching aid. It not only helps teachers teaching, but also helps students independent learning and uses as teaching resource. The teaching aid can be widely used in descriptive geometry. Related Articles | Metrics

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Machining the Leading and Trailing Surface of Turbine Blades#br# by the Bottom of the Flat-End Cutter Zhang Chun, Ning Tao, Shen Yunchao, Chen Zhitong 2015, 36(6): 834-839.  DOI: 10.11996/JG.j.2095-302X.2015060834 Abstract ( 99 )   PDF (1131KB) ( 200 )   Traditional method of machining leading and trailing edge surface of turbine blades with a flat-end cutter is to use the side edge of the cutter to cut the workpiece, by which the strip width will be very narrow when the cutter traces along the tangential direction of blade cross-section curve, because the cross-section curve′s curvature radius of leading and trailing edge surface is too small. By studying on the factors influencing the machining strip width of convex surfaces, it was found that the strip width will be wider if the bottom of flat-end cutter is used. A new flat-end cutter positioning method using the bottom of the flat-end cutter to cut the leading and trailing edge surface is proposed to maximize the strip width by optimizing the two cutter positioning parameters. Machining simulation experiment on an aero-engine demonstrates the feasibility of this method in increasing the strip width of leading and trailing edge surface. Related Articles | Metrics

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Cutter Location Calculation Based on the Four Offset Method of Flank#br# Milling for Undevelopable Ruled Surface Yan Tao, Liu Zhibing, Wang Xibin, Fan Yong 2015, 36(6): 840-845.  DOI: 10.11996/JG.j.2095-302X.2015060840 Abstract ( 84 )   PDF (720KB) ( 203 )   The existing method of five-axis flank milling to machine undevelopable ruled surface is researched, through the analysis of the geometric characteristics of the undevelopable ruled surface, a new method is proposed to calculate the cutter location data of five-axis flank milling with undevelopable ruled surface impeller. The global error optimization between the tool envelope surface and the design surfaces is the goal, and a method to calculate the cylindrical cutter location when flank milling the undevelopable ruled surface is established, putting forward a four-point method to determine the initial cutter location, optimizing it using the least squares method, establishing cutter correction model to further optimize the cutter location to reduce the over-cut error. By analyzing the example, it is proved that processing error can be reduced to some extent through this method. Related Articles | Metrics

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Rapid Design and Implementation of Technics in Drawing Die Oriented by#br# Automobile Covering Components Liu Wei, Ye Futian, Wan Youhao, Zhou Xionghui 2015, 36(6): 846-855.  DOI: 10.11996/JG.j.2095-302X.2015060846 Abstract ( 82 )   PDF (3633KB) ( 307 )   Design and manufacture of the covering components is an important issue in automobile industry. Aiming at its rapid design, this paper achieves the goal using the minimal workload by modifying and replacing certain key components within the pre-designed templates according to practical needs for the actual production to obtain the expected design result. Firstly the parts in covering components are classified into four types, according to which the templates are created with technics and design knowledge embedded. Faced with a new design, the most important operation is to replace the key components in the template, and then the system will automatically append the related information onto them. Related curved surfaces are then extended or trimmed to adapt to the needs. Later experiments validate that the proposed method can effectively reuse the past experiences, reduce errors and finally improve the quality of design. Related Articles | Metrics

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An Approach of Process Planning Based on Bat Algorithms Fan Xiaoliang, Wu Xuehua, Zhao Ailin, Wang Jinfeng 2015, 36(6): 856-861.  DOI: 10.11996/JG.j.2095-302X.2015060856 Abstract ( 90 )   PDF (360KB) ( 237 )   An improved bat algorithm is employed to optimize the process planning for the complicated part to improve the efficiency and quality in process planning. A feasible bat encoding and decoding strategy is designed based on traditional process route representation method from the features to processes. The mapping matrix of process route and bat positions in the search space is constructed, and an initialized approach of bat population is designed. A modification for the local search of bat algorithms (BA) is executed to explore the search space. And displacement and mutation operation for local optimal solution are executed to diverse the population. Simulation experiments verify the feasibility of the proposed algorithm for process planning. Related Articles | Metrics

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3D Ear Point Clouds Recognition Using Sparse ICP Wang Sen, Wang Lu, Hong Jinghui, Li Sihui, Sun Xiaopeng 2015, 36(6): 862-867.  DOI: 10.11996/JG.j.2095-302X.2015060862 Abstract ( 176 )   PDF (632KB) ( 336 )   A novel 3D ear recognition method is proposed in this paper. Firstly, using the PCA and SVD algorithm to normalize 3D ear point clouds model, and adjust the position and posture of all ear point cloud models in the database. Then, based on the Iannarelli system, we extract four local feature regions of 3D ear model, and match them with Sparse ICP algorithm. Finally we match 3D ear models according to the distance between their corresponding points. The experiments show that our algorithm has higher recognition accuracy and efficiency compared with other algorithms. Related Articles | Metrics

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Assessment of Sensor Positions Based on Numerical Simulation Chen Min, Zhang Jingying, Li Xiaofeng, Jia Tao 2015, 36(6): 868-871.  DOI: 10.11996/JG.j.2095-302X.2015060868 Abstract ( 82 )   PDF (584KB) ( 240 )   Using numerical simulation, the models of high-speed projectile penetration of concrete target board with sensors in different positions are built and then imported in HyperMesh to get the finite element models. The time-domain signals of sensors at three different locations are acquired by LS-DYNA. Comparison is made among these signals by the method of frequency-domain analysis. And it turns out that different installation locations in the projectile test device have different influences on the frequency constitute of the overload signals. Conclusions have been made that when the sensor posits in the back of test device, penetration deceleration on rigid-body is clearer and high frequencies is smaller. Related Articles | Metrics

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Generation Method of Symmetrical Pattern Based on#br# the Plane Symmetry Group Zhao Haiying, Chen Hong, Ye Ruisong 2015, 36(6): 872-878.  DOI: 10.11996/JG.j.2095-302X.2015060872 Abstract ( 101 )   PDF (1867KB) ( 278 )   Fabric design is a kind of complex texture pattern, with winding curve, regular and irregular geometrical patterns as the main pattern. Although the pattern generation methods of paper-cut design and fractal pattern have a lot of research work, the computer automatic generation method for fabric design characteristics in Xinjiang still exists many challenging problems. Considering the difficulties of stylized model building of Xinjiang fabric pattern, the method that uses pattern symmetry as the key index of pattern generation is proposed, build the variable and invariable mapping of cyclic group and dihedral group, study the representation of pattern symmetry, prob the relationship between mapping space of group and symmetric graph using symmetric patterns. Through the simulation experiment of mapping group, the symmetrical design with chaos attractor is drawn. Experiments show the generation method can improve the symmetry of pattern and rich the pattern design of fabric. Related Articles | Metrics

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A Heuristic Algorithm for Two-Dimensional Bin Packing#br# with Guillotine Constraints Yao Yi Lai Chaoan 2015, 36(6): 879-886.  DOI: 10.11996/JG.j.2095-302X.2015060879 Abstract ( 91 )   PDF (341KB) ( 242 )   A heuristic approach for two-dimensional bin packing problems with guillotine constraints is proposed to minimize bin usage by maximizing space efficiency through the strategy of value correction. This heuristic algorithm firstly assigns higher values and packing priorities to items considered more difficult to pack into residual spaces, then selects packing spaces in descending order of unused area, and finally expand or merge residual small spaces and add unusable space to the residual adjacent space set, so as to improve the utilization rate. Simulation experiments on benchmark test sets suggest that the approach can work effectively and rivals existing other 2DBP methods. Related Articles | Metrics

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Technics Design System Based on Full Three-Dimensional Model for#br# Complex Electromechanical Product Chen Xingyu, Zhang Xiangxiang, Cheng Wusi, Zhang Hongqi 2015, 36(6): 887-895.  DOI: 10.11996/JG.j.2095-302X.2015060887 Abstract ( 97 )   PDF (1655KB) ( 232 )   3D-CAPP system based on the mixed construction of B/S and C/S is put forward and designed in view of the problems of machining complexity, long design cycle and unintuitive browse chart for high precision, laminose and abnormity cavity components of complex electromechanical products. The system structure and work flow are presented. The key technology of unit identification, combination sash identification and 3D annotation of technics information, dynamic technics model constitution based on manufacture process and 3D technics card constitution in building of technics MBD model is researched. Finally, an application example is provided. It is showed that by using uniform model in design and manufacture process development cycle can be shortened and cost be reduced. Related Articles | Metrics

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Discrete Element Simulation of Movement Characteristics for Particle#br# Material on Transportation Process Liu Yu, Zhou Jiawei, Zhang Xiaoling 2015, 36(6): 896-902.  DOI: 10.11996/JG.j.2095-302X.2015060896 Abstract ( 88 )   PDF (784KB) ( 226 )   In order to reveal the movement rule and influence factors of unloading trajectory for particle material on transportation process, the transportation model of belt conveyor is built using discrete element method. The transportation and projection behaviors of particle material are simulated, and the analysis of the movement velocity and projection trajectory is finished. The analysis results show that there are three phases including accumulation, projection and impact when particles are transported on the belt conveyor. In the impact phase, the velocity and direction of particles are changed continuously because of the impact between particle and dam-board or particle and other particles. The change of velocity and direction is the main influence factor for particle locations after falling to ground. According to the feeding sequence, particle materials are divided into the initial feeding particles, the middle feeding particles and the last feeding particles. The middle feeding particles are disturbed by other particles both in the projection and impact phases. Therefore, there are large differences among the unloading trajectories of the middle feeding particles as well as the locations after falling to ground. The important reason influencing transportation efficiency is the large energy loss caused by impact. Related Articles | Metrics

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Modeling of Virtual Assembly and Disassembly Process Based on#br# Selective Disassembly Wang Hao, Zeng Hong, Zhang Jundong, Gao Yuefeng 2015, 36(6): 903-908.  DOI: 10.11996/JG.j.2095-302X.2015060903 Abstract ( 90 )   PDF (833KB) ( 218 )   To solve the problem of not considering the selective disassembly in the current virtual disassembly system based on the hierarchy model and relationship model, the skipping disassembly path was introduced which developed and optimized the original hierarchy model and relationship model. The sequence planning of the disassembly model after introducing the shipping disassembly path was carried out. And the combination and reduction of disassembling units in the course of disassembly decision was described. Finally, the selective disassembly algorithm was established based on the relationship model. With the marine oil separator for example verification, the verification results showed that the model could solve the problem of selective disassembly very well. So this work has a certain reference value for the development of the related application system. Related Articles | Metrics

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A Zero Color Image Watermarking Resisting Strong Cropping#br# Attacks Using Quaternion Representation He Bing 2015, 36(6): 909-919.  DOI: 10.11996/JG.j.2095-302X.2015060909 Abstract ( 117 )   PDF (1860KB) ( 211 )   For some zero color image watermarking methods are insufficient for several attacks of information loss, a zero color image watermarking algorithm based on nonnegative matrix factorization and real matrix of quaternion is proposed. Firstly, three components (R, G, B) are extracted from color image and each component is decomposed. Secondly, the coefficient matrix decomposed is registered in the copyright center and the real matrix of quaternion is used to represent the original color image, also the krawtchouk invariant moments of the real matrix is calculated. Finally, some krawtchouk invariant moments are used to design and construct zero watermarking information. The experimental results show that original color image under strong shear can be recovered by residual shear part. When the area of shearing color image exceed 80%, watermark information can still be extracted correctly. This performance in image clustering and watermark error detection rate by using the quaternion to represent the whole color image is better than using each of three channels of color image processing or gray image directly. Related Articles | Metrics

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A Fast Correcting Method for Warped Chinese and English#br# Mixed Document Images Wang Jingzhong, Sun Ting, Tong Lijing 2015, 36(6): 920-925.  DOI: 10.11996/JG.j.2095-302X.2015060920 Abstract ( 122 )   PDF (3455KB) ( 489 )   Character recognition rate of OCR processing is not well for warped Chinese and English document image. To resolve this problem, a fast distortion correcting method is proposed in this paper. After the process of image preprocessing, the upper and lower boundary of each text line could be obtained by morphological dilation method. Then, the characters in each line are segmented one by one based on the vertical projection information. Every character can be described in a minimum bounding box. After that, the positions of the segmented characters are corrected according to the different structure characteristics between Chinese and English in each line. Finally, the image could be reconstructed. Experiments showed that this correction method could rectify the warped Chinese and English document image quickly and effectively. The OCR rate of the corrected images could be significantly improved. Related Articles | Metrics

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A Land-Cover Classification Method for Airborne LIDAR Data#br# Based on the Normal DS Evidence Theory 2015, 36(6): 926-930.  DOI: 10.11996/JG.j.2095-302X.2015060926 Abstract ( 93 )   PDF (535KB) ( 232 )   In view of the existing methods cannot meet the needs for accuracy and speed during classification, this paper proposes a fast land-cover classification method for light detection and ranging (LIDAR) data based on the non-subsampled shearlet transform (NSST) and normal Dempster-Sharer (DS) evidence theory. At first, the NSST is used to decompose LIDAR source data in multi-scale, and the median filter is used to reduce the noise in high frequency image from each layer, then inverse transformation and fuse the images. Secondly, the normal probability distribution function is built and the mass function of LIDAR data is distributed, and synthesis and decisions are made. Experiment confirmed that the classification accuracy of the proposed method in this paper is 86.12%, while the running time is only 0.46 s. So this is a fast and high precision land-cover classification method. Related Articles | Metrics

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Object Proposals from RGBD Images Fang Shuai, Jin Ren, Yu Lei, Liu Yongjin 2015, 36(6): 931-936.  DOI: 10.11996/JG.j.2095-302X.2015060931 Abstract ( 112 )   PDF (1245KB) ( 234 )   In recent years, object proposals has become a major research area. Object proposals define and train a measure of objectness generic over classes. But the current research about objectness is based on RGB image. We give a measure of objectness via RGBD images. It combines current state-of-the-art RGB objectness, and design two objectness cues based on depth image, then use a Bayesian framework to combine them. At NYU Depth dataset we demonstrate that the combined objectness measure performs better than any cue alone, and also outperforms traditional objectness based on RGB image. It′s proven that the addition of depth map can better optimize objectness. Related Articles | Metrics

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Viewpoint Navigation Techniques for Virtual Assembly Environment of#br# Large-Scale Products Xiong Wei, Wang Qinghui, Huang Zhongdong, Xu Chenyang 2015, 36(6): 937-943.  DOI: 10.11996/JG.j.2095-302X.2015060937 Abstract ( 82 )   PDF (5375KB) ( 221 )   A high-efficiency navigation strategy is proposed for virtual assembly environment of large-scale products. Based on the theory of cognitive psychology and ergonomics, a workspace of human hand is constructed. Then the workspace is divided into object operation space and viewpoint navigation space. Finally a motion mapping relationship between human hand and viewpoint is developed. It has been proven by experiments that the users can easily navigate the virtual environment in the virtual assembly process. So the two interactive modes, object operation and scene navigation, can be integrated seamlessly. Related Articles | Metrics

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Random Circles Optimization Filling Algorithm of Material Two#br# Dimensional Microstructures Simulation Chen Zhen, Zhou Jinyu 2015, 36(6): 944-949.  DOI: 10.11996/JG.j.2095-302X.2015060944 Abstract ( 101 )   PDF (532KB) ( 198 )   Geometric modeling is one of the main factors affecting the accuracy of material properties calculation by finite element method. Using simple geometric entities, such as circles, to simulate discrete objects is demonstrated well. Beyond the great simplifications in the geometrical calculation, it can provide an approximate model within acceptable error. Material properties not only depend on the average grain size, but also are influenced by the grain size distribution significantly. Random circles packing algorithm designed in this paper ensured these circles′ radius following a certain probability distribution. Normal circles generation method and generating new circle based on the interference types were analyzed. This algorithm not only avoided the interference completely, but reduced the separation greatly. Compared with existing filling algorithms, the filling density of this algorithm was improved obviously. Related Articles | Metrics

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Development of Collision Detection Simulation System for Suspension#br# Type Climbing Conveyor Line Based on NX/Open Zhao Yushan, Guo Hui 2015, 36(6): 950-954.  DOI: 10.11996/JG.j.2095-302X.2015060950 Abstract ( 124 )   PDF (4486KB) ( 296 )   In the structure design of suspension type conveyor line having uphill and downhill function, to predicate and effectively avoid the dynamic collision of the pendants running in the slope have been enterprise′ urgent needs. In order to meet the requirement of parametric design on parts and visual collision detection for the conveyor line, a simulation system is developed for rapid collision detection for the climbing pendants with the data interface NX/Open API. The system is helpful to modify the modeling parts by the way of parameterization, and realize automation of virtual assembly and motion simulation for the climbing conveyor. Finally, the collision is eliminated and the structure is optimized through once more simulation test and its effect feedback under different parameters. Related Articles | Metrics

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Clustering Method of Virtual Machine in Cloud Computing#br# Based on Dynamic Programming Zhu Yanjun 2015, 36(6): 955-959.  DOI: 10.11996/JG.j.2095-302X.2015060955 Abstract ( 105 )   PDF (272KB) ( 251 )   Fast and efficient implementation of multiple virtual machine cluster is greatly significant to enhance processing ability of cloud computing. In this paper, a new clustering method is proposed for virtual machine with general principle of virtual machine cluster and dynamic programming strategy. First, all virtual machine resources are performing in ascending order according to default discriminant function. Second, virtual machine at center position of ascending set is selected as starting point of clustering, and dynamic programming strategy begins from two directions. Clustering principles are based on dynamic programming criterion. Experimental results show that cluster method based on dynamic programming has a fast speed and a stable effect. Related Articles | Metrics

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Research and Teaching Practice on Blended Interactive Courseware for#br# Mechanical Drawing Xu Guoyu, Lan Chaofeng 2015, 36(6): 960-965.  DOI: 10.11996/JG.j.2095-302X.2015060960 Abstract ( 91 )   PDF (5594KB) ( 291 )   Aimed at cultivating creative talents, research on the interactive courseware of the mechanical drawing based on the education idea of Blended Teaching is carried out, and the teaching reform and the resources construction of the mechanical drawing by the interactive courseware are proposed. Its courseware may aid teachers to realize Blended Teaching mode by the combination of teaching in and out of class, of teaching methods with teaching way and of graphics education with engineering practice, and it may aid students to study mechanical drawing by Blended-Learning mode in and out of class. The results show that the blended interactive courseware of mechanical drawing provided effective information technology support for teachers and students, and provided an effective way to cultivate innovative talents. In addition, its courseware won the first prize through live demonstration to promote in the national multimedia courseware competition. Related Articles | Metrics

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The Research and Application of Teaching of Three-Dimensional#br# Constitutes Plugin Based on MAXScript Yu Shuting, Xie Huosheng 2015, 36(6): 966-972.  DOI: 10.11996/JG.j.2095-302X.2015060966 Abstract ( 138 )   PDF (2555KB) ( 205 )   Three-dimensional constitution is one of the most important fundamental courses of art design subjects. Currently, the course face the difficulties of getting and processing materials and the studentsʹ poor sense of space and so on. In order to improve three-dimensional construction teaching, this paper tries to use 3ds Max and its built-in scripting language MAXScript to design a three-dimensional construction plugin. First of all, analysing the constitutes elements and selecting the commonly-used three-dimensional constitution models. Secondly, using MAXScript to make the beautiful three-dimensional models in 3ds Max. And then using MAXScript language and visual MAXScript Editor to design a plugin which can make a lot of virtual three-demensional models. MAXScript is good at batch processing and interface edit. This plugin is applied in art design class in Fuzhou Software Technology Vocational College and Fujian Second Light Industry School. In practice, the teachers and students benefit from the plugin. Using MAXScript to write a plugin for aidding the teaching of three-dimensional constitution can make the teaching more convenient and visual. And it also offers a viable method for the teaching of digital three-dimensional constitution. Related Articles | Metrics

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Research of Adaptive Expansion Algorithm on Pipeline Inner-Surface#br# Panoramic Image Tang Aiping 2015, 36(6): 973-978.  DOI: 10.11996/JG.j.2095-302X.2015060973 Abstract ( 166 )   PDF (590KB) ( 246 )   Panoramic annular lens is a special optical imaging device, which is used in morphology detection of pipeline. It is capable of ignoring hollow image in the radial direction and getting panoramic picture of whole pipeline inside wall. This has absorbed advantages of tangential expansion of traditional unwrapping algorithm, designing a calibration experiment, using edge extraction, Hough transform, and interpolation principle to improve radial development, and obtaining adaptive expansion algorithm to different pipe diameter. Simulation experiment showed that this method is effective to improve radial magnification, and applies to pipes with different diameters. Related Articles | Metrics