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31 December 2013, Volume 34 Issue 6 Previous Issue    Next Issue

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The Computational Basis of Graphics Yu Haiyan, Cai Hongming, He Yuanjun 2013, 34(6): 1-4.  Abstract ( 104 )   PDF (491KB) ( 298 )   By discussing its essence and contradictions, this paper finds out the key to graphics computation and constructs the common infrastructure of graphics. It is concluded that the essence of a figure is not determined by its primitives but by the relations among them. Afterwards, the latest development of graphics computation theories, methods and technologies is introduced. The research characteristics in geometrization and necessity of original basis researches are summed up. A geometric computation theory system and its implementation framework based on the geometrization of geometric problems are proposed, and the latest original theories and mechanisms in constructing stable graphics computation through the way of geometry are elaborated, which include the theories of unifying, researching and developing graphics computation basis, the mechanisims of shape computationand so forth. Related Articles | Metrics

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An Algorithm of Triangulation Based on Monotone Polygon Xu Min, Zhu Erxi, He Yuanjun 2013, 34(6): 6-10.  Abstract ( 98 )   PDF (612KB) ( 323 )   An algorithm of triangulation is proposed based on monotone polygon , which can contain more inner holes. The horizontal(vertical) sectioning lines on the local extreme vertices of boundary in direction of y(x) are made, which can divide the polygon into single connected y(x)-monotone polygons, and then triangulate the monotone polygons. The algorithm considers various singular geometric conditions, therefore is a stable one. Related Articles | Metrics

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Visualization of Radiation Field of Rocket Engine’s Exhaust Plume Qiao Yaobin, Zhu Dingqiang, Zheng Cailang 2013, 34(6): 11-16.  Abstract ( 81 )   PDF (5062KB) ( 244 )   The IR radiation characteristics of exhaust plume is an important target characteristic of rocket engine. Visualization of exhaust plume’s radiation field has great significance to early warning and detection of missile. Firstly, the method of grid sequence and partial polygon fills is improved by dividing rectangle grid into triangles. This arithmetic divides rectangle into four triangles, and then draws isolines and fills nephogram inside the triangle. Secondly, this paper introduces the file format of 3DS models and programs to read and redraw them. Finally, the visualization software based on OpenGL and VC++6.0 is written to draw the isoline and nephogram of rocket exhaust plume’s radiation field, and combine with the nozzle’s 3DS model. That validates the feasibility of the algorithm. Related Articles | Metrics

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Reconstruction of Shoe Last Surface Based#br# on Plantar and Instep Girths Zhao Bao, Hu Xiaochun, Zhang Qingqing 2013, 34(6): 17-21.  Abstract ( 116 )   PDF (561KB) ( 228 )   Aiming at the problem of surface reconstruction existed in the customized design of shoe last for the fitness and comfort, the paper presents an algorithm and its realization of parameterized reconstruction of shoe last surface based on the transformation of cross section of plantar girth and instep girth. The cross section curve of plantar girth and instep girth are transformed to the customized effect through the control of the circumference and height of plantar girth and instep girth. The partial and global spread functions are constructed based on cubic spline interpolation function to realize the spreading of the two girth cross section transformation to the whole shoe last surface in two ways. The algorithm realizes the accurate modification of the shoe last circumference, with the surface smoothness maintained. Having been programmed with MATLAB, it is used to assist shoe last surface reconstruction in a visualized interactive way, with the interface being simple and fast to operate. Related Articles | Metrics

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Bivariate Chebyshev Polynomials and Transformation of Chebyshev-Bernstein Basis on Triangular Domains Jiang Ping, Hong Weiqin 2013, 34(6): 22-29.  Abstract ( 103 )   PDF (1109KB) ( 205 )   For solving least squares approximation problem of Bézier surface effectively and simply on triangular domains in CAGD, we present a polynomial representation, bivariate Chebyshev polynomials, adapted to a triangular domain, with properties similar to the univariate Chebyshev form．We convert and compare this representation to the Bernstein-Bézier and Jacobi representations．We also give some examples to illustrate that the deviation of the bivariate Chebyshev polynomials compared with zero is the least than of the bivariate Bernstein polynomials and bivariate Jacobi polynomials. Related Articles | Metrics

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An Algorithm on 3D Modeling Sketch Creation of Complex Engineering Drawing Liu Hong, Ni Dong, Qiu Jing, Niu Yurong 2013, 34(6): 30-35.  Abstract ( 85 )   PDF (584KB) ( 209 )   An algorithm on 3D Modeling sketch creation of complex engineering drawing is put forward. In the algorithm, the selected view segmentation subalgorithm is proposed. The subalgorithm can not only combine the advantage of three existing mainstream segmentation algorithms and segment view selectively and orderly, but also achieve the purpose of thoroughly partitioning complicated engineering drawing by view partition four times at the most. The improved turn-to-the-left-most rule is presented to enhance the efficiency further. Finally, the examples indicate that the algorithm is effective, can settle some shortcomings which exist when 2D drawing is imported into the existing CAD software and improve the efficiency of 3D geometric model. Related Articles | Metrics

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A Delaunay Triangulation Algorithm Based on Minimum Voronoi Neighbors Meng Xianhai, Cheng Wendi, Xu Bo, Yang Qin 2013, 34(6): 36-41.  Abstract ( 77 )   PDF (893KB) ( 374 )   A node-based algorithm of Delaunay triangulation is proposed, which aims at supplying local triangulation requirements. The algorithm is based on the locality of Delaunay triangulation and its dual Voronoi graph. Local Delaunay meshes are generated by searching Minimum Voronoi Neighbors for each point. The background assistant grid is proposed to improve the efficiency. The theoretical proof, programming implementation and efficiency analysis of the algorithm are given. Finally, several practical applications of the algorithm are introduced. Related Articles | Metrics

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Forming Principle and Inferences of Spherical Involute Tooth Surface for Spiral Bevel Gears Ding Han, Adayi·Xieeryazidan 2013, 34(6): 42-47.  Abstract ( 212 )   PDF (839KB) ( 340 )   From the precise shape of the tooth surface of the spiral bevel gears, the basic components of the spherical involute tooth surface are discussed in detail. On the basis of application of the theory about spherical involute for the spiral bevel gears, the characteristics and shortcomings are analyzed and summarized, and a principle of forming spherical involute tooth surface for the spiral bevel gears is proposed in the paper. Additionally, it makes inferences of its key links namely the generating-line, working tooth profile, and the basic equations of the spherical involute tooth surface, and proposes some approaches for its surface design and manufacturing, in order to provide theory basis and ideas for the research on the spiral bevel gears. Related Articles | Metrics

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Rapid Anhui Styled Architecture Modeling Based#br# on Sub-Topology Generation Xue Feng, Song Wei, Cui Guoying 2013, 34(6): 48-55.  Abstract ( 61 )   PDF (844KB) ( 193 )   Rapid modeling for ancient characteristic building is an important subject of virtual reality research areas, and is also of important cultural significance. This paper summarizs the characteristics of Anhui styled architecture and proposes a rapid modeling method automatically generated on the basis of topology. Then the topology is traversed and rendered to generate Anhui styled building scene model. Finally, some experimental results are presented to show that this method is fit for rapid modeling of Anhui styled architectures. Related Articles | Metrics

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Integrative Technology for Three-Dimensional Structure CAD and CAE of Port Wharf Based on Template Xiong Shenghua, Tang Weiqing, He Tao 2013, 34(6): 56-60.  Abstract ( 61 )   PDF (416KB) ( 241 )   Aiming at integrative problems of three-dimensional structure CAD and CAE in port wharf, the paper studies the integration technology of three-dimensional structural CAD and CAE based on the template characteristics of model independence, rules, execution etc.. It defines section sketch template, three-dimensional entity template, component template and other CAD modeling template, while defines mechanical sketch template, load template and other load modeling template. It defines CAE analysis rules for automatically converting CAD geometry model to CAE unit model, defines load conversion rules for automatically converting engineering load CAD model to CAE load model, defines model template for establishing the relationship of CAE analysis results and CAD model. It implementes the integrated system of port wharf three-dimensional structure CAD and CAE to greatly improve the design efficiency of port wharf, reduce the design difficulty and errors. Related Articles | Metrics

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Research on Hybrid Modeling Technology for CAD Model Liu Aijun, Huang Songbo, Yan Guangrong 2013, 34(6): 61-63.  Abstract ( 83 )   PDF (354KB) ( 302 )   The three-dimensional digital modeling technique mainly has two ways: parametric modeling and direct modeling. But both are defective in practical applications. In this paper, a hybrid modeling technique consisting of the two is presented. This method can reflect the intention of the designers and improve design efficiency better. Related Articles | Metrics

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A New Combined Parametric Design Method Based on SolidWorks Lu Jie, Mi Caiying 2013, 34(6): 64-68.  Abstract ( 97 )   PDF (716KB) ( 264 )   Dimension (parameters) driven method and program-driven method are two kinds of parametric design methods of SolidWorks secondary development. This paper proposes a combined parametric design method after studying and comparing the advantages and disadvantages of the existing two parametric design methods, and it is classified as two forms of series and parallel based on implementation ways. The study shows that it can make full use of the advantages of both dimension driven method and program-driven method. The paper develops a program based on Microsoft Visual C++6.0, which verifies its superiority in designing complex parts. Related Articles | Metrics

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Buses Handle Design Based on Ergonomics Analysis Lyu Zhongyi, Qu Yao 2013, 34(6): 69-73.  Abstract ( 182 )   PDF (522KB) ( 310 )   The design of bus handle is expanded on application of ergonomics principle and human body measurement data. Based on the analysis of existing problems in current products and design, the paper puts forward an improved principle to alleviate dizziness and hidden danger produced by inertia during the vehicle running. Considering the actual situation that different passengers have different heights and advertising effectiveness, combined with the anatomical characteristics of hand and the standing static and dynamic size, it is set out from the aspects of loop, connecting structure, advertising placement, limiting part, material and color of every component. The whole design provides new ideas in improving the use comfort of bus handle and riding environment. Related Articles | Metrics

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Relational Model Design of Recreational Vehicle Li Bing, Deng Xuexiong, Qin Yiming, Li Meng 2013, 34(6): 74-79.  Abstract ( 100 )   PDF (5570KB) ( 202 )   The purpose of this research is to improve the matching degree between RV modeling and user expectations, as well as to reduce design cost. Under the guidance of Kansei engineering idea, this study transforms product modeling and user evaluation into two measurable variables, and uses multiple regression analysis to establish effective equation model between the two, so as to define the specific principles between them. A cylindrical two-dimensional coordinate system is advanced to establish cognitive space of car styling elements. As an improvement and innovation about Kansei engineering idea, this method can help decision-makers predict the marketing response and assist designers to model at concept generation stage. Related Articles | Metrics

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Wavelet Image Compression Algorithm Based on Threshold and Characteristics of Human Eye Wang Feng, Wan Zhiping 2013, 34(6): 80-86.  Abstract ( 113 )   PDF (26828KB) ( 57 )   Image transmission is difficult due to the large amount of data. In response to this problem, according to the wavelet transform efficiency and universality this paper put forward a wavelet image compression algorithm based on the threshold and the characteristics of the human eye. In the low-frequency sub-band of the image, it puts forward a threshold retention algorithm that uses the threshold and visual sensitivity. In the high-frequency sub-band of the image, it puts forward an edge-preserving algorithm that uses the sub-band directional and the wavelet anglesto reduce the redundancy in an image signal while maintaining image quality. The experimental results show that the algorithm can achieve its goals and has advantages of low power consumption. It has good prospects for development in the field of image compression. Related Articles | Metrics

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Image Gray Enhancement Based on Improved Particle Swarm Optimization Algorithm Wang Hongtao, Li Dan 2013, 34(6): 87-92.  Abstract ( 99 )   PDF (1366KB) ( 206 )   Aiming at grayscale image enhancement features, the quantum properties of chaotic particle swarm optimization studies are used. First, the global optimal solution particles update their velocity and position; then the probability density function of quantum effects makes the particle in bound state to appear, with a certain probability, anywhere in the entire feasible search space ; the chaotic state makes the particles change from disorder to order , with the related factors avoiding searching blindness; final grayscale image uses nonlinear mapping curve transformation, and its function is translated into parameters of improved PSO algorithm. The simulation shows the algorithm excellent for image grayscale enhancement better in quantitative evaluation and good in time efficiency. Related Articles | Metrics

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Simulation of Half-Dry Stroke in Chinese Painting Based on Technique of Writing Model Deng Xuexiong, Weng Yingxin, Zhang Wen 2013, 34(6): 93-97.  Abstract ( 91 )   PDF (578KB) ( 205 )   In order to realize the computer simulation of Half-Dry Stroke in Chinese painting, based on the technique of writing, the effect of Half-Dry Stroke is proposed, which is divided into silkiness and plaques respectively, including the decrease of ink, the determination of Half-Dry Stroke areas and the generation of stroke. By detecting ink volume of the stroke model, the reaction of stroke split in the insufficient area is yielded. Based on the main-stroke, a certain number of sub-strokes with identical model are superposed, then the effect of emulating Half-Dry Stroke is realized. Related Articles | Metrics

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Dynamic Performance Analysis and Optimization of High-Speed Elevator Based on Virtual Prototype Technology Wu Hui, Liu Yanbin 2013, 34(6): 98-105.  Abstract ( 70 )   PDF (1065KB) ( 211 )   In order to reduce high-speed elevator vibration to improve its riding comfort, the virtual prototype model of high-speed elevator is set up by Solidworks and Adams. The dynamic analysis and simulation of the whole running situation of the elevator are made. The effect of the main dynamics factors to the high-speed elevator vibration received by sensitivity analysis of the high-speed elevator vibration signal is obtained. The dynamics parameters of the elevator are optimized by frequency domain analysis of vibration signal and natural frequency analysis for multi-body system. The simulation result shows various dynamic characteristics have been great improved after optimization. This simulation result provides reference for improving performance of elevator. Related Articles | Metrics

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Research and Development of Simulation System Based on Web for Wire Drawing Die Sun Pengjie, Zhai Fenlou, Liu Dongxu, Yan Jiali, Ning Jing 2013, 34(6): 106-109.  Abstract ( 64 )   PDF (665KB) ( 250 )   Secondary development of Abaqus based on the Python Scripting can effectively realize the pre-processing, analysis and post-processing for simulation analyses which need cumbersome repeated operations. However, using this method, customers still need to spend a lot on software purchase and installation. In this paper, a Web based online simulation system for wire drawing die is developed. Using this system, costumers only need to submit analysis parameters, such as mold parameters, material parameters and process parameters, through web. Analyses are conducted on a cloud back end and reports can be automatically generated. Customers can download these analysis reports and animation. This kind of operation model saves customers from software and CAE HR training cost. Importantly, this model can decrease the CAE technology barrier. Related Articles | Metrics

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Analysis of Sense of Drawing Factors in Modern Graphics Teaching Liu Yancong, Ma Xiaoli, Yi Peng 2013, 34(6): 110-113.  Abstract ( 90 )   PDF (446KB) ( 193 )   To explore the effective teaching methods in engineering graphics, the concept of sense of drawing and its intrinsic characteristics are investigated and enriched in the paper，based on the profound understanding and awareness of the sense of drawing factors from psychological perspective. To create teaching models that meet the cognitive law better and improve the graphics culture level and the ability of thinking of students, the approaches to cultivate sense of drawing are explored according to the practical teaching work. Related Articles | Metrics

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Exploration and Practice on New Teaching Mode of Mechanical Design and Drawing Yang Guanghui, Cao Tong, Wan Jing, Fan Bailin, Xu Qian 2013, 34(6): 114-117.  Abstract ( 107 )   PDF (441KB) ( 291 )   For improving teaching quality further in limited teaching time, teaching contents are separated into three parts that are compulsory part, self-studying part and selective part, which can help to emphasize the important part, improve students’ self-studying ability and realize hierarchical and classified teaching. For inspiring the learning interests of students and avoiding the boring indoctrinated mode in teaching, various teaching modes and methods are used such as stretching teaching method and discussing teaching method. Some proper methods such as case teaching method are found and used to solve the problems that teachers are difficult to describe and students are difficult to understand. Test training is emphasized in class and it can let most students be trained properly. The five-unification and individualized teaching are emphasized in teaching course management. Related Articles | Metrics

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Innovative Design of Teaching Contents and Methods for Projection Fundamentals Liu Qingke, Shu Tian 2013, 34(6): 118-121.  Abstract ( 76 )   PDF (421KB) ( 211 )   Based on the analysis of teaching contents and methods of projection fundamentals in the course of engineering drawings, and on the discussion of the innovation and enhancement in projection fundamentals, some insufficiencies in the theory and method of form and structure projection are revealed. Based on the principles of undertaking and going beyond the tradition, and exploring vivid and varied rules and methods as soul of “Fundamentals and Enhancement of Engineering Drawings”, some new ideas, new theories, and new methods on the form and its projection are put forward, and some measures to promote further reform and progress in teaching contents and methods in the projection fundamentals are discussed. Related Articles | Metrics

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Study and Practice on Practical and Innovative Teaching Content and Method for Architectural Engineering Graphics Liu Kefei, Tang Xiaohong, Wu Qingding, Hu Jinsong 2013, 34(6): 123-129.  Abstract ( 90 )   PDF (1386KB) ( 261 )   In order to train the creative thinking and design expressing of students, the training of ability and quality should be given an equal status as knowledge teaching in graphics education. Combined with the teaching situation and practice, the teaching content and method of architectural engineering graphics and the check and evaluation of teaching effect have been reformed, and the teaching mode which takes configuration design, practice and innovation as mainline has been proposed. The results show that the new system can enhance the space thinking ability, configuration design ability, innovation ability and engineering consciousness of students, the teaching quality has been improve significantly. Related Articles | Metrics