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31 August 2012, Volume 33 Issue 4 Previous Issue    Next Issue

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Research on the visualization of the function-tree’s similarity reasoning process Liu Xiaoping, Chen Xin, Lu Qiang, Tang Yiming 2012, 33(4): 1-6.  Abstract ( 64 )   PDF (453KB) ( 198 )   Similarity reasoning can be used to enrich the design information contained by function-tree and enhance the possibility of obtaining innovative design solutions. The way that visualization is used to aid the similarity reasoning is discussed in this paper. First, the rules of mapping function-tree to appropriate visual model are confirmed. Second, the human-machine interactive aid corresponding with the process of similarity reasoning is provided to obtain real time feedback. Lastly, an application example testifies the availability of similarity reasoning method and the improvement of reasoning results caused by introducing visualization into similarity reasoning. Related Articles | Metrics

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Modeling of three-dimension fractal plant based on X3D Zhang Jie, Cai Wenqi 2012, 33(4): 7-12.  Abstract ( 63 )   PDF (331KB) ( 197 )   Plant simulation is a popular and difficult issue in computer graphics these years. In order to conveniently and quickly browse the 3D plant which is realistic and interactive on web, a mathematic model of plant-modeling based on determination L-system, parameter L-system and the original recursive algorithm is proposed from the aspect of the plant physical structure in this paper. X3D and JAVA are chosen to generate a three-dimensional plant model quickly and easily after giving related parameters. The modeling of the branch structure of tree, the leaf arrangement and leaf is realized in this paper. Related Articles | Metrics

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Fast visualization algorithm for huge 3D-finite element models Zou Jing, Ji Hongguang 2012, 33(4): 13-19.  Abstract ( 86 )   PDF (400KB) ( 230 )   According to the features of huge 3D-FEM models, basic requirements of visualization and key algorithms are summarized. Then, a simple and reliable algorithm of fast rendering is prepared for different tasks of grid, unit, slice visualization and color contour respectively. Through contrastive testification of specific examples and typical business software by contrast, the feasibility and superiority of the algorithm is initially demonstrated, which can contribute to simplification of preparation for huge FEM program. Related Articles | Metrics

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Projection analysis of intersection of cone and sphere based on CATIA Pan Zijian, Meng Xiangbao, Pan Shuzhang 2012, 33(4): 20-23.  Abstract ( 73 )   PDF (243KB) ( 285 )   The projection construction process of intersection of cone and sphere in some spatial locations is analyzed by the auxiliary-sphere method and projection-transformation method. It provides several samples and some clues for the implementation of intersections of basic and complex rotational solids by auxiliary-sphere method. The correctness involved in above is verified by 3D hybrid modeling on CATIA software, in which it makes the construction process pictorial, perfect and convenient. Related Articles | Metrics

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The curve of second order formed by projective line pencils and their degenerate types Liu Fuping, Ding Yong 2012, 33(4): 24-27.  Abstract ( 80 )   PDF (361KB) ( 218 )   The paper uses, for the first time, the graphic method to systematically express the existence of three forms of line pencils in the projective plane. The line pencils show a certain pattern in the formation of second-order curve: the two pencils of lines with infinite points as the base form a hyperbola; the two pencils of lines with both finite and infinite points as the base form a parabola; the two pencils of lines with both finite points as the base form a hyperbola, a parabola or an ellipse upon rotating any one of them. These conclusions lay a theoretical foundation for the realization of the transition between the second-order curve. Related Articles | Metrics

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Research on cubic Bezier curve detection algorithm based on Hough transformation Sun Wenyun, Han Bin 2012, 33(4): 28-32.  Abstract ( 106 )   PDF (275KB) ( 328 )   Similar to the classic Hough transformation for analytic curves such as line (segment), circle (arc), ellipse, parabola etc, a new cubic Bezier curve detection algorithm is provided in this paper. A method of feature modeling for discrete Bezier curve and a new fast Hough transformation for analytic curves using R-Function is presented. The algorithm set up model of shape parameters from the target bitmap which will be detected. Then it detects the position, size and direction of a same curve in complex images. The experimental results show that the algorithm detects any cubic Bezier curve effectively. It has a better accuracy than the generalized Hough transformation which is wildly used for detecting curves at present. Related Articles | Metrics

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Research on rectangle packing problem based on Monte Carlo method Zheng Rongjie, Zhang Pengcheng, Cui Hailiang, Li Guoshun, Luo Haibing, Liu Xintong 2012, 33(4): 33-36.  Abstract ( 90 )   PDF (201KB) ( 227 )   The rectangle moves freely according to the random step generated by Monte Carlo method in the region to be packed in. When the rectangle moves, it is confined in the region to be packed in automatically, which makes the calculation of feasible region become simple. After the feasible region is obtained, the rectangle is packed in successfully by the placement function. Experiments show that above ninety percent of the region to be packed in is filled with rectangles. Related Articles | Metrics

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Feature analysis and modeling of cooling passages transition section in turbine blade Xi Ping, Zhu Qian, Zhang Baoyuan 2012, 33(4): 37-41.  Abstract ( 74 )   PDF (545KB) ( 243 )   Cooling passages transition section is a kind of complex surface feature in aero-engine turbine blade. Through feature analysis of cooling passages transition section, an effective modeling method is proposed, which is proved to obtain the smooth transition of cooling passages with G1 continuity. The main parameters are determined as well. Eventually the parametric design of cooling passages transition section is realized via programming, which achieves rapid modeling and modification of the feature. Meanwhile, it provides some good references to the parametric design of other complex features in turbine blade. Related Articles | Metrics

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Method on similar extension of arbitrary function trees based on matter-element theory Liu Xiaoping, Lu Jingting 2012, 33(4): 42-49.  Abstract ( 70 )   PDF (363KB) ( 183 )   Function models are the core objects of conceptual design. Function tree is a typical function model which is widely used. Defects are found while the similarity of arbitrary function trees is calculated by existing method. Therefore, the concept of disjunctive normal form tree is proposed based on Boolean algebra. After that two solutions of Disjunctive normal form tree are presented. And a method on similarity calculation of arbitrary function trees is described. Thus, the application of function trees’ similar extension is expanded. As a result, the solution space is enlarged, and the possibility to attain innovational solutions increases. At last, an application example demonstrates the effectiveness of the method. Related Articles | Metrics

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IGES data exchange algorithm for assemblies based on DAG representation and production Rules Huang Jing, Wang Bin, Hu Kaimo, Zhang Hui 2012, 33(4): 50-58.  Abstract ( 117 )   PDF (401KB) ( 239 )   The Initial Graphics Exchange Specification (IGES) is one of the most widely used neutral file standards. The related researches have mainly focused on the translation of single parts, however, few of them dealt with the IGES form for assemblies, which appear frequently in design. In this paper, we first summarize the IGES-file form of assemblies in most popular CAD software and then propose an IGES data exchange algorithm for assemblies based on Directed Acyclic Graph (DAG) Representation and Production Rules. This method standardizes the process of analysis of IGES forms, which enhances its commonality and extensibility. Moreover, the correctness of the method can be formally verified. With this method, we implement the pre-processor and post-processor for the multi-file IGES representation for assemblies. The experiments conducted in our geometry modeling system TiGems 7.0 show that the algorithm is fast and robust. Related Articles | Metrics

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Research and development on computer aided design and optimization system of steel grating Liu Ming, Ning Tao, Zhu Zengli 2012, 33(4): 59-63.  Abstract ( 83 )   PDF (349KB) ( 209 )   Steel grating is widely used in construction, chemical industry, water conservancy and other fields. There are many problems in its design and manufacturing process that restrict the production efficiency. The system integrates the functions of automatic SG-Layout, automatic workload calculation, optimization for cutting and so on to optimize the whole process of design and manufacturing of steel Grating. This greatly improves the efficiency of production. A project example is given to prove the practicability and reliability of the system. Related Articles | Metrics

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Automatic generation of pipeline engineering drawing based on space projection Luo Nianmeng, Gong Xiaohan, Zhu Lin 2012, 33(4): 64-70.  Abstract ( 68 )   PDF (318KB) ( 181 )   To meet the needs of rapid generation of engineering drawing of boiler pipelines for industrial plant, based on the given information of pipelines, taking the factor of projection regular pattern into consideration, an algorithm about automatic generation of working drawing of pipelines based on anchor points in 3D space is proposed and implemented. The algorithm can determine the direction of Principal View, break the pipe automatically and complete the judgment and generation of dihedral angle view and partial view automatically. The reliability and effectiveness of this algorithm is verified in a practical application on enterprise production. Related Articles | Metrics

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Estimation of face rotation based on depth data Jiang Jianguo, Hu Zhenzhen, Zhan Shu 2012, 33(4): 71-75.  Abstract ( 90 )   PDF (356KB) ( 484 )   A novel method of calculating the rotation of face is proposed based on the 3D facial depth information. Facial feature points are extracted by the depth map and its corresponding gray image according to differential geometry theory, curvature algorithm and intensity features generated by face data. And then the three pose angles of the face in the space will be calculated. Experimental results show that the proposed algorithm can achieve an accurate estimation of face rotation with the variation of pose and provide a priori knowledge for face recognition and facial expression analysis. Related Articles | Metrics

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Research on camera calibration used for building reconstruction Yu Ye, Liu Xiaoping, Xu Wei, Han Jianghong 2012, 33(4): 76-72.  Abstract ( 54 )   PDF (496KB) ( 211 )   Vanishing point has many geometry attributes and exists abundantly in building scenes, based on this, a camera calibration method is proposed using vanishing points, which is especially used for building reconstruction. Lots of geometry constraints are discovered, such as the constraint relationship between vanishing points and camera matrix, the origin of world coordinate system and camera matrix. Then through matrix reconstruction and Euclid reconstruction, the camera matrix is calculated. Through decomposition of this matrix, the inner and outer parameters of the camera are achieved. In this method, no calibration object is needed; besides, it also has the advantage of simple calculation process, high calibration speed. Experiments show that it can meet the needs of building reconstruction in virtual reality system. Related Articles | Metrics

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A realistic 3D facial reconstruction system based on measurement from two viewpoints Rong Jian, Zhao Cuilian, Fan Zhijian, Chen Xiaobo 2012, 33(4): 83-87.  Abstract ( 70 )   PDF (412KB) ( 206 )   Facial modeling is a hot research topic both in computer graphics and 3D reconstruction fields. This paper realizes facial measurement from two viewpoints with two groups of CCD and structural light projectors, ensuring the scope and the integrity of the measurement data. Pointing to the geometrical and texture data of measurement, this paper developes a visualized software platform for data processing, which can accomplish processes for two viewpoints including thinning, segmentation, jointing and meshing, and after texture mapping a realistic 3D facial model can be reconstructed. Finally, with the integration of the measurement system and the software process platform, an integrated system for 3D facial reconstruction is formed, and the flexibility of the system is proved by the experiment. Related Articles | Metrics

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An improved method of natural texture synthesis Li Dajin 2012, 33(4): 88-92.  Abstract ( 62 )   PDF (405KB) ( 265 )   Algorithm of natural texture synthesis is an efficient and excellent synthesis method based on sample images, especially applicable to natural plant. However, the problem of candidate pixels going out of sample image borders is not solved ideally, which mainly causes the obvious seams between two pixel blocks. This paper presents a modified algorithm of natural texture synthesis. The pixels that cause invalid candidate points are all at the border of the sample image, the pixel regions at the border of sample are replaced by the other pixel blocks within the sample in our algorithm. The replacing one is of the same shape and size as the target one. Also the pixel colors of a replaced region and the target one are well matched along an irregular line. In synthesis process, the growth of a pixel block can turn to a replacing pixel block when touching the boundary of the sample image, and thus the seams among texture blocks are obviously reduced, and the output image quality is highly improved. Related Articles | Metrics

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A fast and effective method of iris image preprocessing Gong Junhui, Chen Aiping, Tang Yongqi, Huang Feng 2012, 33(4): 93-97.  Abstract ( 77 )   PDF (396KB) ( 220 )   To solve the problems that the iris localization is too long, the inner edge of iris is not ideal circular, and eyelids or eyelashes commonly exist, a novel method of iris image preprocessing is presented. The false edge points of iris are greatly reducing by mathematical morphology operator to process the iris image. Finally, eyelashes and eyelids are detected by double line fitting. Testing on the CASIA－IrisV3 database, experiment results show that the proposed algorithm has a high performance on speed and precision, and eyelids and eyelashes detection algorithm can remove eyelid and eyelashes reasonable and effectively. Related Articles | Metrics

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Modeling and simulation of the resonant tuning fork with the consideration of additional quality and axial force Gou Zhanshe, Song Chunmiao, Zheng Shixue 2012, 33(4): 98-102.  Abstract ( 60 )   PDF (322KB) ( 172 )   To solve the theoretical calculation problem of the resonant tuning fork with the consideration of axial force and additional quality, three theoretical models of the resonant tuning fork are deduced. These three models are proposed by using Rayleigh law and the law of conservation of energy with the consideration of the following three cases: the axial force, the additional quality, both the axial force and the additional quality. On this basis, the finite element simulation method is used to verify the correctness of these theoretical models. A number of simulation results show that the relative error between calculation results and simulation results are less than 1%, which proves that the theoretical calculation is correct. Related Articles | Metrics

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Space mapping precision analysis and simulation in navigation system robot-assisted surgery Cao Tong, Xu Qian, He Li, Chen Hanqing 2012, 33(4): 103-109.  Abstract ( 47 )   PDF (410KB) ( 180 )   The main source of space mapping error in the minimally invasive surgical robot navigation system is analyzed. Four types of the space mapping error are described in detail. Through the simulation analysis it is concluded that the benchmark positioning error and the target mapping error is proportional, and the target mapping error is relatively small when the benchmark positioning error range in two dimensions is small. Using simulation analysis to influence the distribution way of marked points space mapping precision based on affine coordinate, two kinds of marked point distribution modes which strongly affects space mapping precision are obtained as the coplanar distribution and the marked point distribution in which the target cannot be surrounded in the distribution scope. Coplanar distribution can lead to aberration when solving mapping matrix by using affine coordinate system and can result in mapping error distortion mutations. When targets are out of the surrounding areas of marked points, the target mapping error will be greater than space mapping when targets are in the surrounding areas of marked points. Related Articles | Metrics

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Dynamic simulation analysis of plated CBN hard gear-honing processing based on LS-DYNA Li Yunfeng, Zhang Mandong 2012, 33(4): 110-113.  Abstract ( 76 )   PDF (277KB) ( 218 )   When plating CBN hard gear-honing processing with standard involute tooth profile, generally there are a “mid concave” error near pitch circle of the work-piece tooth, and a “dig root” error near its root. Since the factors of the error formation are complex, it is difficult to calculate errors with an exact analytical method. Therefor, by the help of Pro/E and ANSYS/LS-DYNA software, the analysis of plating CBN hard honing process is dynamically simulated. Through picking up the datum from analysis results, the von mises stress distribution values are listed along engaging points on the tooth surface. Due to the existence of relations between the von mises stress and the tooth profile errors, the internal factors of the tooth profile error formation of work-piece can be revealed, and the location and extent of the tooth profile errors can also be discovered. It provides a theoretical basis for necessary modificatioin of the gear-honing-tool tooth profile, and the results are consistent with the actual processing. Related Articles | Metrics

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Product assembly guidance based on augmented reality Wang Junfeng, Xu Chi, Li Shiqi 2012, 33(4): 114-120.  Abstract ( 90 )   PDF (344KB) ( 420 )   Aiming at the assembly guidance in augmented reality environment, an uniform augmented-assembly-oriented information model is build to manage visual text, geometric and feature information during assembly process in augmented reality environment. A marker-based tracking is adopted to realize the registration and localization of virtual and physical product part. The depth images of both virtual and physical scenes are used to handle occlusion between virtual and real objects in assembly process. The assembly guidance information is superimposed on the real time assembly video by using registration information of parts. A demonstration system is developed and the assembly guidance process is analyzed and described in augmented reality environment. Related Articles | Metrics

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Research on form design of product image based on conjoint analysis Li Yongfeng, Zhu Liping 2012, 33(4): 121-128.  Abstract ( 99 )   PDF (542KB) ( 253 )   In order to design the products that meet consumers’ affective needs, the product image form design method based on conjoint analysis is proposed. Firstly, multidimensional scaling and cluster analysis are chosen to ascertain the typical samples, and the attributes and levels of them are identified through morphological analysis. Secondly, product kansei images are determined via factor analysis, and then are integrated by form attractiveness. Based on this, correspondence analysis is used to explorer the relationship between kansei images and attributes. Finally, conjoint analysis is applied to build the mathematical model between them. An experimental study of office chair is conducted based on the presented method, and the results suggest that this method is valid and feasible. Related Articles | Metrics

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Integrative frame for computer-aided structural design and analysis Xiong Shenghua, Xie Zhengjian, He Tao 2012, 33(4): 129-135.  Abstract ( 57 )   PDF (432KB) ( 183 )   Aiming at integrative frame of computer-aided structural design and analysis, the integrative frame based on uniform data model and components is proposed, in which the bottom level is integrative structural model database of CAD/CAE; the middle level is the components, including of geometric modeling components, visual interactive components, third-party CAD components, third-party CAE components, and so on; the top level is application layer, including subsystems of structural design and structural analysis. The frame supports functions of spatial structure modeling, models management, finite element analyzing, finite element calculating, and so on. Finally, the frame is applied for spatial structural design and finite element analysis of port terminals. Related Articles | Metrics

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Study on historical development, status quo and future progress of engineering drawings Lin Dajun 2012, 33(4): 136-139.  Abstract ( 104 )   PDF (200KB) ( 553 )   In addition to meeting present-day development requirements, a worthwhile discipline should anticipate trends and includes new contents. Anticipating trends is sometimes difficult but an attempt is made in the paper. The development of engineering drawing is the continuity of the history. The current state of engineering drawing cannot meet the demands brought by rapid development in terms of both science and technology and production and manufacturing as well. It，s required to carry out experiments for engineering drawing, which can drive the development of courses. As a result, the positive circulation with theory development by experiment and vise versa will be established, which will be an efficient channel of sustainable development for engineering drawing. Related Articles | Metrics

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Teaching research and practice of creative configuration design in the course of engineering drawing Wang Fenghong, Chen Chikun, Chen Jinchang 2012, 33(4): 140-146.  Abstract ( 67 )   PDF (377KB) ( 400 )   Teaching of creative configuration design has been the important way to train students with creativity in the course of Engineering Drawing. On the basis of analyzing teaching aims and design estimation of configuration design, the basic teaching method of it is discussed deeply. Related Articles | Metrics

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Education reform of comprehensive experiment course for aircraft manufacturing engineering specialty in universities Yan Guangrong, Cheng Wei, Ning Tao 2012, 33(4): 147-150.  Abstract ( 65 )   PDF (182KB) ( 181 )   An education reform program of comprehensive experiment course for aircraft manufacturing engineering specialty is presented in this paper. This program includes 14 independent experiments which belong to four technologies series. The four technologies series include the aircraft digital design and manufacturing method, metal sheet hot forming way, digital flexible assembly technique and composite material component design and manufacturing method. These experiments involve not only traditional aircraft manufacturing process, but also latest information technology in the aircraft development. It can promote the undergraduate’s ability of action and understanding of the specialty knowledge when they finish all the experiments. Related Articles | Metrics

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Research of protection scope and the 3D model based on complex lightning protection Wang Fenghong, Chen Chikun 2012, 33(4): 151-155.  Abstract ( 99 )   PDF (377KB) ( 171 )   The model reconstruction method of protection scope based on complex lightning protection is discussed and researched. The basic thinking is provided about reconstructing the protection scope by the 2D contour lines of the plane of the protection scope. By using the theory of grounder, the creating method of 2D contour lines on the protection plane is analyzed and researched on the basic of envelope principle and the corresponding math model is given. Then, the 3D reconstruction method based on 2D contour lines is researched. The above method is not only fit to design the complex lighting protection scope but also fit to design the simple one, and provide a new way to the design of lighting protection scope. Related Articles | Metrics

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Research on steganography based on dot-matrix character code and entity color for engineering graphics Yang Yujun, Yang Yimei, Yin Xiangfeng 2012, 33(4): 156-162.  Abstract ( 56 )   PDF (401KB) ( 159 )   Aiming at the problem of copyright protection for digital engineering drawing and the deficiency of robustness and practicability of the steganography for digital engineering drawing, an algorithm of steganography based on dot-matrix character code and entity color for engineering graphics is proposed. In the algorithm of steganography, the hidden message is firstly coded by dot-matrix, and the character of the message has the image characteristic property. Then the coded information is encrypted by a two-value chaotic sequence generated by Logistic map system. To realize the information hiding and self-checking, the encrypted information and its checksum are embedded into the entity color of engineering drawing combining with the HVS. The experiment results show that the algorithm has a higher embedded capacity and a better robustness for some attacking of moving, rotation and edit. And the problem of copyright protection for digital engineering drawing is solved in a good way using the algorithm. Related Articles | Metrics