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26 February 2010, Volume 31 Issue 1 Previous Issue    Next Issue

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Research and Training on Graphics Thinking TONG Bing-shu 2010, 31(1): 1-5.  Abstract ( 147 )   PDF (384KB) ( 285 )   The situations of research on graphics thinking in the teaching of engineering graphics are investigated for the past 30 years, and the importance of graphics thinking research to the reform and development of engineering graphics education is pointed out. Through summarization and further research, the definition of graphics thinking is defined, the graphics thinking methods and its characteristics are illustrated, the process model of graphics thinking is presented, and the methods for graphics thinking training are described concretely. Some problems of graphics thinking for the future research are described. Related Articles | Metrics

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Survey on Non-Photorealistic Rendering Technology for Artistic Images QIAN Xiao-yan 2010, 31(1): 6-12.  Abstract ( 210 )   PDF (476KB) ( 422 )   Non-photorealistic rendering (NPR)，which is belong to computer art category, is a new problem in computer graphics and image processing, and much attention is given to this field from home and abroad. A detailed survey of current techniques for NPR is given. Firstly, the studying meaning and studying range are presented. Secondly, the related key technologies are summarized in detail. Some typical NPR algorithms are compared and classified. Finally, some key research issues that need further research efforts are pointed out. Related Articles | Metrics

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The Weight-Lighten Design for the Frame of C-Type Hydraulic Press#br# Based on the Iterative Optimal Method XIE Feng, SHEN Wei-lei, LIN Ju-guang 2010, 31(1): 13-19.  Abstract ( 187 )   PDF (560KB) ( 378 )   The three-dimensional parameterized model is constructed by analysis for strengthen and rigidity of C-type press body. On this base, the target and restriction functions of weight, stress and deformation of the body are formed by cross design and principle of least square method. The iterative optimization is carried out by ANSYS’ finite element software. The optimal dimensions for the C-type press body are obtained on the assurance of body’s strengthen and rigidity. Related Articles | Metrics

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Research on Lightweight Design of Press Frame Structure Based on Parametric FEA ZHAO Han, CHEN Xing-yu, DONG Yu-de, ZHANG Jan, YU Lai-hong 2010, 31(1): 20-25.  Abstract ( 153 )   PDF (541KB) ( 271 )   The parametric finite element model of hydraulic pressure (HP) is built. Also, orthogonal experiment is used to simulate actual work condition for calculating stress and angular distortion. Using data from related experiments, the linear relation between HP’s main structural parameters and its maximal stress, maximal angular distortion and weight is get according to the regression model. The regression model is established based on least square method. Under Kurd-Tark condition, the optimal mathematic model is built. Also, reasonable lightweight design plan is proposed through simulative calculation. It is showed that the effects of lightweight design are obvious, the improved plan is in accordance with actual work condition. Related Articles | Metrics

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Parameterized Design for the Components of Straight Bulk Cement Container Based on UG/KF CHEN Yan-hui, LIANG Hui, XU Wu-bin, LI Bing 2010, 31(1): 26-29.  Abstract ( 144 )   PDF (514KB) ( 224 )   The structure features of the straight bulk cement container are analyzed, and then parameterized design for the components of the straight bulk cement container is developed under the environment of UG software. The knowledge models of cement container’s components are set up based on UG/KF. The system has been applied in the practice and can save the designer’s time and decrease the develop periods of new products. Related Articles | Metrics

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Path Planning for Mobile Robot in Unknown Environment Based on Cubic Spiral Bug Algorithm KANG Liang, ZHAO Chun-xia, GUO Jian-hui 2010, 31(1): 30-38.  Abstract ( 154 )   PDF (515KB) ( 386 )   An improved path planning for mobile robot in unknown environment is proposed, in which the Bug algorithm and rolling path planning are combined. The cubic spiral for mobile robot path tracking is well studied here and some excellent characteristics are found. Then the cubic spiral curve is used to smooth the collision-free path by defining the cost functions of path for smoothness. Therefore the mobile robot is easy to track and the application field of mobile robot is extended. At last the proof of convergence and completeness is given. Simulation results verify the effectiveness of this method. Related Articles | Metrics

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Development of Parameterized Design and Unfolding System for Sheet Metal Pipes HE Wei, MAO Xin 2010, 31(1): 39-43.  Abstract ( 110 )   PDF (578KB) ( 268 )   A system for parameterized design and unfolding of sheet metal pipes has been developed on the basis of the analysis for the computer-aided conditions and manufacturing requirements of the sheet metal industry at home and abroad. It integrates the functions of part design and unfolding, and contains all-around design objects as well as precise design results. Some critical techniques are introduced, such as modeling tragedy, the abstraction of interface curves, the mapping of the interface curves to mid-layer curved face, and interface design. At last, the examples of application are illustrated. Related Articles | Metrics

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Study on the CAD Technology of Roller Gear Cam MU Xiao-yun 2010, 31(1): 44-47.  Abstract ( 121 )   PDF (490KB) ( 240 )   Calculation of the surface coordinates of roller gear cam is accomplished by using VC++ language based on the working principle of roller gear cam. The CAD model of roller gear cam is constructed by using the point-cloud processing function of Imageware software and the solid modeling function of UG software. This work lays the foundation for the followed virtual design and manufacturing. Related Articles | Metrics

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Model Database Construction for Virtual Assembly System LIU Guo-wei, JIA Qing-xuan, SUN Han-xu, SONG Jing-zhou, GAO Xin 2010, 31(1): 48-53.  Abstract ( 143 )   PDF (482KB) ( 211 )   Because the amount of 3D models is so large in virtual assembly system, which make the difficulty to store the models, so the data type of LOB (Large Objects Binary) in Oracle is used for storing 3D models. A virtual assembly platform is constructed with VC++, and OpenGL is used to display 3D models. Related Articles | Metrics

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2D Geometric Constraint Solving with Directed Graph WANG Shi-ping, GUO Lian-shui 2010, 31(1): 54-60.  Abstract ( 138 )   PDF (524KB) ( 218 )   In order to solve the over-constrained problem and enhance computational efficiency, an algorithm, which is based on the constructing directed constraint graph, revealing constraint conflict, then reversing the direction of the related constraint to balance the constraint graph, and finally sorting the graph to get the solving sequence of geometric entities, is presented. The method of balancing constraints can help transforming the over-constrained problem into well-constrained. Related Articles | Metrics

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Research on Graphics Matching of Multiply Connected Region Based on Triangulation LIU Xiao-ping, HE Shi-shuang 2010, 31(1): 61-66.  Abstract ( 129 )   PDF (448KB) ( 205 )   It is important to solve the multiply connected region graph matching problem in engineering drawings recognition and interpretation, which is compounded by multi-polygon. First, the multiply connected region graph is represented by encircle polygon and connected polygon; then, the position problem of included connectivity is solved by achieving triangulation according to short-distance, non-cover and including principles. In the matching process, first the contour is positioned by matching encircle polygon, and then the connected region is removed successfully by matching connected polygon, at last the rotated and scaled graphics matching problem is accomplished by shrinking the graphics region step by step. This method has been applied in the automobile wire harness drawing recognition and makes good effect. Related Articles | Metrics

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Study on Feature Recognition Algorithm Based on Graph Decomposition LIU Xiao-ping, WU Min, JIN Can 2010, 31(1): 67-71.  Abstract ( 157 )   PDF (393KB) ( 274 )   The key problem of CAD/CAE model transformation lies in how to decompose models to the simplest elements. Such element owns similar gridding property which can weigh computing error and time. And for this reason this paper proposed a feature recognition algorithm based on graph decomposition and decomposed the attributed adjacent graphs to many connectivity components, and then formed the volumetric feature in terms of these connectivity components. This algorithm is not limited to the feature type; it would return a desired result of model decomposition only if the resolvability of the vertex is controlled reasonably. And meanwhile, by using this algorithm we could acquire entity characteristics and remove or replace feature in the level of characteristics, which can simplify the model conveniently. Related Articles | Metrics

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Skewed Symmetry Face Detection and Application in Quadric Surface Solid WANG Xiang, DING Yun-liang, LI Jing 2010, 31(1): 72-78.  Abstract ( 113 )   PDF (490KB) ( 198 )   Symmetry plays a very vital role in 3D reconstruction. Skewed symmetry depicts a real symmetry viewed from some (unknown) viewing direction. Skewed symmetry detection could reduce the complexity of 3D recovering. A method is presented to detect the skewed symmetry surface of quadric surface solids, which enlarges the skewed symmetry detection theory put forward by SUGIMOTO to all quadric surfaces. If all the symmetry axises are found, the skewed symmetry surface can be generated using the turn to-the-left-most approach. This algorithm has no requirements on projection direction, thus expands the coverage of 3D reconstruction. Related Articles | Metrics

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Research on the Method of Simulation of Real-Time Water Surface Based on GPU LIU Xiao-ping, XIE Wen-jun 2010, 31(1): 79-83.  Abstract ( 125 )   PDF (477KB) ( 234 )   A method of real-time water surface simulation based on GPU is proposed. Using this method real-time water wave can be constructed without displacement texture, and then be rendered with the Fresnel effect and the illumination model. As the rasterization is done before the fragment processing of GPU, the burden of rendering will not grow with the size and precision of water area. According to the GPU’s high capability of calculating, this method can achieve the real-time rendering. Related Articles | Metrics

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Research on Outdoor Augmented Reality Technology Based on Vision Registration HUANG You-qun, LI Zhi-peng, HU Chao-bo 2010, 31(1): 84-87.  Abstract ( 145 )   PDF (515KB) ( 273 )   Now outdoor augmented reality technology mostly uses the registration method by hardware trackors for exploration and exhibition problems. In order to meet the application requirements in outdoor planning and design, registration method based on computer vision could be used which is more interactive. Coordinates of calibration points, which is essential to vision registration, can be calculated using computer vision method assisted by range finder, so it can be applied in image-based outdoor planning and design. The registration process can be simplified by setting camera coordinate system to coincide with world coordinate system. Outdoor planning and design will benefit from all of these works. Related Articles | Metrics

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Least Error Approximation and Its Application for Free-Form Curves Based on Multi-Knots Spline U Kin-Tak, HUANG Jing 2010, 31(1): 88-93.  Abstract ( 108 )   PDF (599KB) ( 370 )   Muti-knots spline has good locality and least square method has good global characteristics for data fitting. Therefore, the stability and numerical accuracy of least square method based on multi-knots spline approximation could be reached effectively. This paper combines the advantages of them and completes the model building of the free-form curves with least approximation error based on multi-knots spline. Meanwhile, this method is applied to the free-form-curve fitting of some plane and space (even with noise) data and Geometry Shape Skelectonization. The fitting results show that the least approximation effect is good. Related Articles | Metrics

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Blend Surface Design Based on Helmholtz Equations BAO Chong-bing, HAN Xu-li 2010, 31(1): 94-99.  Abstract ( 129 )   PDF (533KB) ( 250 )   The problem discussed in this paper is about the second-order and fourth-order of Helmholtz equation of a class of periodic boundary problem and its difference solution in the transition surface design, which is different from traditional method of PDE in the second-order and fourth-order partial differential equations. It has more free items than the traditional method, so more shape control parameters can be adjusted in the surface design. The focused attention is to discuss the changing effects of equation coefficients and boundary conditions to the surface shape. If boundary curves and related tangent vectors are given by the designer, then the surface can be constructed. Related Articles | Metrics

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Geometric Convergence of Degree Elevation of B-Spline Curves ZHU Ping, WANG Guo-zhao 2010, 31(1): 100-103.  Abstract ( 128 )   PDF (559KB) ( 183 )   Degree elevation of B-spline curves is an essential measure for communication between CAD systems. The sequence of B-spline’s control polygon convergences to initial B-spline curve is similar to the Bézier curve. The convergence proof of B-spline curve is obtained based on the degree elevation algorithm by the bi-degree B-spline. In contrast to traditional methods, degree elevation algorithm by bi-degree B-spline can be interpreted as corner cutting process, so degree elevation of B-spline curve has obvious geometric meaning. The result makes B-spline curve obtained by geometric corner cutting algorithm as Bézier curve. Related Articles | Metrics

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Rational Approximation of Offset Surface by Univariate S-Power Basis ZHANG Li, TAN Jie-qing, LIU Zhi 2010, 31(1): 104-109.  Abstract ( 98 )   PDF (752KB) ( 310 )   A new algorithm for approximating offset surfaces by using univariate symmetric power basis is presented. It uses symmetric power basis to approximate u directional curves of tensor product Bézier surface, then it gets a set of offset approximating curves. From fixed v value of these curves, it will get a set of data points. The paper gets v directional approximating curves which get through these data points by anti algorithm of control points. Finally, rational approximating offset surface is got by using skinning surface algorithm. The algorithm is easy and solves the integral tolerance. Numerical examples show that it can achieve good effect with the raise of the S-power basis’ degree. Related Articles | Metrics

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Surface Fitting Based on C1 Natural Neighbor Interpolation NIE Zhi-feng, ZHOU Shen-jie, WANG Kai, KONG Sheng-li 2010, 31(1): 110-115.  Abstract ( 138 )   PDF (729KB) ( 236 )   C1 natural neighbor interpolation can be realized when C0 non-Sibsonian interpolation is introduced in the Bernstein-Bézier surface representation of a cubic simplex. The principle and properties of C1 natural neighbor interpolation are described and the surface fitting is given. The Voronoi diagram can adjust the spatial discrepancy caused by irregular data and data of varying density, so even for the scattered data, C1 natural neighbor interpolation can get accurate fitting results. Related Articles | Metrics

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3D Reconstruction of Vessel Based on Fusion of IVUS and X-Ray Angiograms SUN Zheng 2010, 31(1): 116-123.  Abstract ( 135 )   PDF (794KB) ( 313 )   An approach for fusing X-ray angiogram and intravascular ultrasound (IVUS) images to accurately reconstruct vessels based on compensatory disadvantages of both imaging modalities is proposed. Firstly, the pullback path of IVUS catheter is reconstructed from angiogram pair acquired at the origin of the path. Then, vessel wall boundaries in cross-section of lumen are extracted from IVUS images with a semi-automatic snake-based method. Lastly, the relative changes in orientations of IVUS frames are determined with a Frenet-Serret frame-based model. Absolute orientation of each IVUS frame along the pullback path is obtained by using a non-iterative statistical optimization algorithm. Consequently, reconstruction of vessels based on fusion of two types of data is implemented. Experimental results with clinical data demonstrate the validity. Possible errors and computation cost are also discussed. Related Articles | Metrics

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Studying on High Dynamic Range Image Encoding and Tone Mapping Technology FAN Jin-song, FAN Yan-bin, PEI Ji-gang 2010, 31(1): 124-128.  Abstract ( 152 )   PDF (642KB) ( 443 )   Based on the discussing of the fundamental concept and acquisition technology of High Dynamic Range Image (HDRI), several encoding technical methods and approaches of HDRI are analyzed and studied, and characteristics and applications are explored respectively. Meantime, tone mapping technology of HDRI is also discussed, and the calculation of background intensity is studied. Finally, the application fields of HDRI are prospected and forecasted. Related Articles | Metrics

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Shadow Removal in Remote Sensing Infrared Image Clustering Based on Retinex Method WANG Zi-wu, LI Jing-shi, WU Jing, FANG Guo-tao 2010, 31(1): 129-134.  Abstract ( 185 )   PDF (682KB) ( 204 )   The infrared remote sensing always plays an important role in the application of detecting urban virescence. But in the city, complex ground-objects, a mass of shadows caused by high-buildings and a large number of color ground-objects form disturbing sources for extracting vegetation information. To solve above problems, Retinex and the chromatics are discussed and studied with colorimetry. A processing method is designed based on the idea of better maneuverability and low complexity to resist disturbance and to extract vegetation information from infrared remote sensing images. Related Articles | Metrics

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Omni-Directional Image Making Based on Fisheye Lens DENG Song-jie, ZHOU Song-bin, CHENG Tao-bo 2010, 31(1): 135-138.  Abstract ( 184 )   PDF (455KB) ( 874 )   Base on an optimized fast outspread theory, fisheye lens image can be transformed into omin-directional image. It works by transforming the coordinates with the bicubic interpolation and inner stitching. There is no need of stitching some photos taken by camera or using cylindrical theory and parameter of apparatus in this method. In the end, the effectiveness of the method is demonstrated by the final examples by way of MATLAB. Related Articles | Metrics

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An Optimum Algorithm for Electron Probe Micro-Analyzer Image Fusion Based on Bandelets Transform LI Xiang, HE Jian-feng, LIU Feng-yu 2010, 31(1): 139-144.  Abstract ( 164 )   PDF (437KB) ( 167 )   The Electron Probe Micro-analyzer (EPMA) image, as a key source of the sample micro-morphological elements, has already been widely used in sophisticated analytical techniques. After studying on the situation of the EPMA application and its characteristics, as well as adaptive multi-scale analysis characteristics of Bandelets transform, a second generation Bandelets transform is proposed in this paper. The experiment shows that the second generation Bandelets transform, which has better practical value, can support rapid and robust image decomposition and provide near-linear algorithm. Related Articles | Metrics

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Development of Human Machine Interaction Simulation System Based on Virtual Reality Technology CAO Wen-gang, WANG Rui, ZHANG Hong-qi, CHEN Di-jiang, PENG Wu-si 2010, 31(1): 145-149.  Abstract ( 204 )   PDF (483KB) ( 436 )   Aiming at the deficiencies of some virtual simulation systems in aspects of interaction, real time response, data collecting etc., a virtual simulation system which enables users to interact with virtual operation object is developed based on various hardware/software techniques. After importing design objects through data transition, the system can dynamically collect the data about the interactive operation for measuring interaction performance and evaluating design quality. Experimental results demonstrate that the system is feasible. Related Articles | Metrics

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Key Technology of Laying Rectangular Tiles along Reference Line on Ship Hull WU Nian-qing, ZHAO Yao, YUAN Hua 2010, 31(1): 150-155.  Abstract ( 114 )   PDF (432KB) ( 191 )   Reference line coincides with the water line and extends throughout the whole length of ship hull, while offset points are laid along the rib-lines. Such an approach of developing the curved surfaces of ship hull along two mutually perpendicular directions is proven to be better than the former way of flattening the surfaces merely along the rib-lines. The new process is implemented and validated on the platform of MDT software, showing that both the speed and quality of laying tiles on the whole ship hull are remarkably improved. Related Articles | Metrics

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Study on Drawing Method of Transition Curve in GIS WANG Ming-sheng, YAN Xiao-yong 2010, 31(1): 156-150.  Abstract ( 126 )   PDF (409KB) ( 222 )   Transition curve is a constituent element of highway or railway horizontal alignment. A drawing method of transition curve in GIS is presented. Based on the fundamental of curve drawing method in Computer Graphics and geometrical feature of clothoid, a polylines approach is used to plot transition curve. A precise formula for determining segments number of the polylines is ratiocinated by Compound Trapezia numerical integral method. Further more, conversion method of arc length and point coordinate in transition curve is delivered. This drawing method of transition curve has been programmed in Supermap GIS and is found that the precision and efficiency can fill the requirements of application. Related Articles | Metrics

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Implementations of New Standard——“Indication of Surface Texture” in Engineering Graphics Textbook LING Ling 2010, 31(1): 161-167.  Abstract ( 143 )   PDF (536KB) ( 373 )   “Geometrical product specifications (GPS) —— indication of surface texture in technical product documentation (GB/T 131-2006)” is a general standard in GPS series of new generation, and it stipulates the marking rules of surface texture requirement in technical product documentation. Three main surface texture parameter groups about evaluating surface texture in GPS series standards are concisely introduced in the paper. The detailed analysis and balance for the change of the marking rules of surface texture in new and old standards are performed and their distinct something is pointed out. Simultaneously, the marking rules, extending new contents, marking examples, and explaining and reading about new standard are listed out. These can provide the consultations for correct comprehension and implementation about new standard for teachers engaged in engineering graphics teaching and for compiling and revising engineering graphics textbooks. Related Articles | Metrics

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The Connotation and Purpose of Art Education on the Basis of Graphics SUN Rui, LI Ming, REN Li-sheng 2010, 31(1): 168-171.  Abstract ( 107 )   PDF (438KB) ( 213 )   Based on the teaching of graphics for years and the art education in graphics in recent years, from the viewpoint of art education, the paper points out that the connotation of graphics is the expression of life consciousness and life activities, and includes the very combination between engineering and art, and hastens new technologies and view and so on. The purpose of graphics is also discussed which is to enhance artistic training and creativity for students. According to the author′s experiences, it can be concluded that only if students stick to explore and keep trying, they can get the achievements under such a teaching mode, which takes graphics education as basis and art education as aid. Related Articles | Metrics

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Reverse Modeling and Analysis of Automobile Engine Fan Blades ZHAN Chang-qing, LIU Su 2010, 31(1): 172-175.  Abstract ( 155 )   PDF (470KB) ( 188 )   Taking fan blades of automobile engine as object, the fan triangular mesh model is obtained by a laser scanning equipment “ATOS”. Using triangular mesh data preprocessing technology and approach of blend surface feature extraction, the fan surface digital model is reconstructed, and then checked with smoothness and precision. The experiment results show that this reverse modeling method can meet design requirements. Related Articles | Metrics

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The Methods of Generating Technical Documents Based on AutoCAD FENG Shen, FENG Yun-fei 2010, 31(1): 176-180.  Abstract ( 106 )   PDF (402KB) ( 247 )   The most engineering technical documents are consisted of texts and engineering drawings. Two questions are discussed, i.e. how to insert AutoCAD drawings into the text files, and how to accede characters into AutoCAD drawings. The methods described above have the reference values for making engineering documents. Related Articles | Metrics

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Parametric Design for Standard Parts Based on Correlation Relations ZHANG Xue-chen, ZHANG Qi-hui, FAN Ru-xiang, XU Jie 2010, 31(1): 181-184.  Abstract ( 143 )   PDF (507KB) ( 673 )   Parametric design methods of geometric modeling are investigated. A method of parametric design for standard parts based on correlation relations is proposed. In order to achieve parametric design of standard parts, correlation among components is built using association parameters. A parametric design process of tapered roller bearing is given based on CATIA, which verifies the feasibility of the method. Related Articles | Metrics

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Protein Similarity Comparison and Classification Based on Multiple Characters Framework XU Zhan, DONG Hong-wei 2010, 31(1): 185-190.  Abstract ( 139 )   PDF (529KB) ( 186 )   Protein similarity comparison is an important way to study protein structure and function. Many methods are proposed which are capable of comparing all available protein structure. Being different from those methods, a new method based on multiple characters is provided. There are four characteristics and some internal relationships among the four characteristics. So a method based on fuzzy equivalent matrix is proposed in which the four characteristics are considered comprehensively. Related Articles | Metrics