Table of Contents

31 December 2012, Volume 33 Issue 6 Previous Issue    Next Issue

---

For Selected:

Download Citations EndNote Ris BibTeX

Toggle Thumbnails

Select

Research on converse construction of axonometric projection model Lin Dajun 2012, 33(6): 1-6.  Abstract ( 89 )   PDF (450KB) ( 202 )   The application of the projection transformation method to establish a mathematical solution model of Axonometric Projection is adopted to propose a general telescopic coefficient method to realize the real size of axonometric Projection conversely Then, three-dimensional entity modeling is conducted to achieve original design from human brain against computer constraints. Finally, the 2D drawing is produced for engineering processing. All these processes are done by computer, making it in more accordance with the essence that design starts from 3D Image. Related Articles | Metrics

Select

A parallel algorithm for generating Voronoi diagrams based on point-set adaptive grouping Wang Jiechen, Pu Yingxia, Cui Can, Chen Gang, Ma Jinsong 2012, 33(6): 7-13.  Abstract ( 78 )   PDF (381KB) ( 276 )   This paper presents a parallel algorithm for generating Voronoi diagrams based on point-set adaptive grouping. The algorithm works in the following steps. Firstly, the method of binary tree spitting is adopted to adaptively divide the planar point-set into groups. The points within each group independently generate Voronoi diagram, named the Voronoi sub-diagram. Then, the boundary points in each group are collected to construct another Voronoi diagram, called boundary-point Voronoi diagram. Finally, for each boundary point, two polygons in which the boundary point is located are extracted respectively from the Voronoi sub-diagram and the boundary-point Voronoi diagram. These two kinds of polygons are merged to ultimately realize the combination of Voronoi sub-diagram. Considering that the generation of Voronoi sub-diagram is the most time consuming part and each sub-diagram is independent from each other, the parallel computing technique is used to accelerate the generation of Voronoi sub-diagram. Theoretical analysis and tests show that this proposed algorithm is an efficient method of generating Voronoi diagram. Related Articles | Metrics

Select

A fast line clipping algorithm against circular windows based on adaptive identification and table-based intersections retrieval Lu Tong, Su Feng, Yang Ruoyu 2012, 33(6): 14-23.  Abstract ( 68 )   PDF (358KB) ( 182 )   Existing circular window clipping algorithms are inefficient for many complex real-life applications like intelligent CAD and graphics recognition/understanding systems, due to their large number of graphical primitives, complicated geometrical constraints and real-time interaction requirements. This paper presents a fast line clipping algorithm against circular windows. The proposed algorithm is composed of three parts: adaptive identification of invisible lines based on tangent lines separation, fast identification of visible lines based on polygons cutting, and fast line-arc intersections generation based on predefined tables retrieval. Experimental results demonstrate that the proposed algorithm greatly reduces the computational cost to clip lines by adaptive line-circle situation analysis and replacement of time-consuming operations with simpler ones. Related Articles | Metrics

Select

GPU Raycasting based on curveture Yuan Bin 2012, 33(6): 24-30.  Abstract ( 71 )   PDF (562KB) ( 198 )   Curvature-based Volume rendering is a useful method to help scientists to find features in data set and to design new mathematics model. In this paper, Fast GPU Raycasting for curvature, in which data are reconstructed with tri-linear filtering and tri-cubic filtering and derivatives, curvature and shading are computed on demand, is implemented in GPU. As a result, computing on demand speeds up the method based on tri-cubic filtering; the method based on tri-linear filtering is faster than the method based on tri-cubic filtering; the method based on tri-cubic filtering can acquire more smooth result. We can select interactive camera setting, transfer function and curvature function to highlight interesting feature with the method based on tri-linear filtering and then render high quality image with the method based on tri-cubic filtering. Related Articles | Metrics

Select

The developable tangent curved surface of a surface patch and mapping analysis between them Mao Xin, Yang Jinglin, Ma Mingxu 2012, 33(6): 31-37.  Abstract ( 63 )   PDF (430KB) ( 227 )   Based on the developable curved surface theory of differential geometry, the method to construct the developable tangent curved surface passed a curve on a curved surface is put forward, the expression form and type division of the developable tangent curved surface is given, the overall and partial mapping analysis between two surfaces is realized through establishing the mapping relationship of them and the deformation of surface is grasped accurately. The method is validated by example and can be applied to the design and approximate development of curved surface and surface texture mapping. Related Articles | Metrics

Select

Research on attractive factor approach in rectangular packing problem Wang Jinmin, Qi Yang 2012, 33(6): 38-44.  Abstract ( 98 )   PDF (334KB) ( 165 )   The attractive factor approach, which is one of the location function approach, has gotproduces better results in the packing problems. This paper researches the attractive factor approach and gets some basic properties of it as follows: Such as the 3D image of the location function is a plane, the points with equal values of the location function are on the same straight line, the rectangular items are piled in a corner by the attractive factor approach, and so on. In addition, a manual rapid-packing method is given by studying the geometry significance of the pack-in point. In the end, the property which is about the of being an invisible attractive factor is obtained by studying the effect of the position of the attractive factors. Related Articles | Metrics

Select

Polygon clipping algorithm based on dual-strategies tracing and grid partition Wang Rongfeng, Liao Xuejun 2012, 33(6): 45-50.  Abstract ( 61 )   PDF (288KB) ( 183 )   An effective algorithm for polygon clipping which supports simple polygons including concave polygons and polygons with holes inside is presented in this paper. This algorithm can be used to calculate set-theoretic differences and union of two polygons. Most analogous algorithms are classifying point of intersection by entry points and exit points, then generating output polygons by tracing vertex. Different from these algorithms, this paper classifies point of intersection by normal point of intersection and vertex of intersection, and designs different tracing strategies for them. By using these strategies alternately and recursively, a steady tracing process to cope with degenerate input is putted forward. To improve efficiency of edge intersection, which is the bottleneck of polygon clipping, it partitions the polygon that has more numbers of edges to grids and brings forward an algorithm for edge partition based on Bresenham line-drawing algorithm. At the end of this paper, the algorithm is compared with the existing algorithms and the result shows that it has higher speed than others. Related Articles | Metrics

Select

Efficient hybrid scan-conversion algorithm for circles drawing Zhang Shengnan, Niu Lianqiang, Chen Xin 2012, 33(6): 50-58.  Abstract ( 94 )   PDF (324KB) ( 209 )   In order to improve speed of circles drawing, some multi-step or run-length slice algorithms are proposed. Based on careful analysis of the characteristics of raster-scan circles, a simple and fast method to calculate lengths of slices is presented in this paper. In the new algorithm, double-step control is mainly used for larger horizontal run-slices, and mixed single-step and double-step control is adopted for complicated pattern and run-slices with 45° angle, furthermore, each horizontal run-slice is output at once, only about 2.9 times basic operations are needed for once stepping on average. Experiments and analysis shows that the new algorithm is significantly faster than previously published ones, and its’ derivation can be gained in a simple manner. Furthermore, it can be implemented with hardware since no complex operations are involved, and can be developed to draw other conic curves. Related Articles | Metrics

Select

W-M fractals interpolation with freeform surface based on arc-length parameterization Liu Yuandong, Wang Qinghui, Liu Lin, Xiong Wei 2012, 33(6): 59-64.  Abstract ( 109 )   PDF (569KB) ( 218 )   A method of modeling W-M fractal freeform surfaces by superposing W-M fractals on parametric surfaces is proposed in this work. First, the significance of superposing W-M fractals with parametric curves and surfaces is pointed out; then the importance of utilizing arc-length parameterization for the superposing is described, and followed by our specific algorithm with which the fractal simulation with freeform surfaces is achieved; at the last section, an anisotropic approach for presenting freeform fractal surfaces is developed and with demonstrated graphics simulation. Related Articles | Metrics

Select

Research on parametric design of single anchor leg mooring system Chen Jinchang, Deng Huadong 2012, 33(6): 65-68.  Abstract ( 110 )   PDF (239KB) ( 360 )   The construction of single anchor leg mooring system is analyzed. Constraint definitions are made based on the parts’ structure dimensions in the system, and the constraints among the parts are analyzed, by which the parametric design of the system is simplified and the constraints analysis of the structure becomes quite clear. After the above, the relating analysis of the parts is made to help to determinate the order of the modeling. At last, a parametric design system of single anchor leg mooring is developed based on the software of SolidWorks. Related Articles | Metrics

Select

Module partition method based on complex network theory Yang Gelan 2012, 33(6): 69-75.  Abstract ( 82 )   PDF (362KB) ( 240 )   In order to improve the defects in present methods of module partition, complex network theory is applied in the module partition, and a new method of module partition is proposed based on community structure algorithm. The network map is constructed according to the relationship of Structural unit, then the module partition is completed using of GN algorithm. The method and steps of the proposed method are explained, then, the validity and feasibility of the proposed method is proven using a case study on automobile engine module. Finally, it summarizes the main work and mentions the weakness in the research and the prospects of the future research. Related Articles | Metrics

Select

Optimal design of heterogeneous objects based on graded finite elements Wu Zhenhua, Zhao Han, DongYude, Liu Jiqing 2012, 33(6): 76-81.  Abstract ( 78 )   PDF (626KB) ( 263 )   In order to achieve the optimal design of heterogeneous objects with the characteristic of spatially graded layout, the concept of two-phase graded finite elements is established. Lagrangian shape functions are employed to interpolate the volume fractions of the constituent materials. Adaptive lower bounds of the design variables are introduced to control the local gradients in the nodal neighborhoods. Method of moving asymptotes is used to solve the optimization problem for specific functionalities and objectives. A metal clip is analyzed and optimized to verify the feasibility and robustness of this approach. Related Articles | Metrics

Select

Dynamic design and optimization of elevator based on virtual prototype technology Liu Wen, Liu Yanbin, Zhang Xing 2012, 33(6): 82-87.  Abstract ( 67 )   PDF (547KB) ( 235 )   In order to optimize dynamics parameters for improving the riding comfort of elevator, Solidworks and Adams are combined to set up the virtual prototype model of elevator. Dynamic simulation and analysis are carried out for this model under certain constraints and drivers. Dynamics parameters are optimized by frequency domain analysis of vibration signal and natural frequency analysis for multi-body system of elevator. The simulation result shows that various dynamic characteristics have been improved greatly after optimization, this simulation result also provides reliable basis for improving efficiency for elevator. Related Articles | Metrics

Select

Research on some problems in 3D simulation of CNC pipe cutting machine processing Ren Qingchuan, He Saisong, Xu Lei 2012, 33(6): 88-92.  Abstract ( 73 )   PDF (278KB) ( 177 )   To test the justifiability of cutting pipe process with CNC machine, OpenGL and 3DSMax technologies are used to achieve the 3D dynamic presentation of process and cutting result by driving the imported 3D static model with the parameters in OpenGL environment. Compared with the traditional method which is based on collision detection to reproduce the shape of pipe intersection, a new mathematical model is presented, and it has been proved to be fast and accurate to calculate the intersection. Related Articles | Metrics

Select

An operation simulation system for spatial parallel robot based on VRML Jia Qinghao, Li Xiaojun, Liu Lin 2012, 33(6): 93-97.  Abstract ( 104 )   PDF (321KB) ( 231 )   Virtual Reality Technology is frequently applied to robot simulation. To point against simulation efficiency caused by large amount of computation of kinematic inverse solution of traditional parallel robot, we use the kinematic parameters of load base to generate IndexLineSet node dynamically, and then, we can solve the length and orientation of guide bar based on this node. A kinematic simulation system is devised by using JavaScript and VRML interactive programming. The simulation results show that the new system is more efficient than traditional method. Related Articles | Metrics

Select

Simulation of brushstroke multi-color in Chinese painting based on technique of writing model Deng Xuexiong, Li Mu, Zhang Wen, Wang Wanqing 2012, 33(6): 98-102.  Abstract ( 71 )   PDF (364KB) ( 199 )   In order to improve the computer simulation of the brushstroke multi-color in Chinese painting, this paper proposes the multi-color effect emulate based on the technique of writing. By establishing a stroke model, the thick or thin of sub-stroke (center writing) is changed, or several sub-strokes (side writing) are superposed which offset a certain distance. Thus the complex process of calculating the color in the stroke area point by point is avoided and the running speed is enhanced. The center writing and the side writing are determined by the angle between brush and paper, and the intelligent technique of writing is realized when the center writing and the side writing are interchanged. Then the effect of brushstroke multi-color emulate is produced by two different techniques of writing. Related Articles | Metrics

Select

A gait recognition algorithm using fuzzy theory decision double-directional two-dimensional principal component analysis Chen Xiangtao, Zhang Qianjin, Zhang Shuangling 2012, 33(6): 103-109.  Abstract ( 75 )   PDF (396KB) ( 186 )   A gait recognition algorithm is proposed based on fuzzy theory classification decision double-directional two-dimensional principal component analysis (DTPCA) for the problems of high dimensionality and difficult classification of mean gait energy image (MGEI) coefficient matrix. A preprocess technique is used to obtain MGEI, which is then divided into some of sub-image blocks, then DTPCA is used to reduce the dimension of mean gait energy sub-image blocks coefficient matrix and improve the recognition speed. The fuzzy theory is introduced to classify the nearest-neighbour classifiers. The proposed algorithm is evaluated on CASIA Gait Database. Experimental results show that the proposed approach achieves a high recognition accuracy and stronger robustness. Related Articles | Metrics

Select

A fast color face recognition algorithm Zhu Jie,Chen Changwei, Yang Wankou, Tang Zhenmin 2012, 33(6): 110-115.  Abstract ( 84 )   PDF (270KB) ( 207 )   Face recognition is an active research area in the artificial intelligence, which has aroused great concern. Multiple color space canonical correlation analysis is proposed based on different color spaces analysis. This paper analyses and discusses the characteristics of Contourlet transform, and, by using the contourlet’s advantage of multiscale, directionality and anisotropy, proposes a novel color face recognition algorithm. First, the source images are transformed into contourlet domain to get the LP and HP images. Then, canonical correlation analysis (CCA) is used to recognize the face. CCA is an efficient projection operator, which can analyze different color spaces to get the biggest correlation. Finally, nearest neighbor classifier is selected to perform face recognition. Experimental results on color AR face database show that the proposed algorithm, which achieves recognition accuracy of above 98%, is more effective and faster than the traditional method. Related Articles | Metrics

Select

The thinking and practice of engineering drawing CAI Wang Jianhua, Hao Yuxin, Liu Lingtao 2012, 33(6): 116-120.  Abstract ( 81 )   PDF (432KB) ( 329 )   With the rapid progress of computer technology and the teaching reform in engineering drawing, Computer Aided Instruction (CAI) has become one of the most important modern teaching methods. Its’ application in the classroom teaching has begun to receive attention widely. By analyzing the advantages and disadvantages of the practice of Engineering drawing CAI, this paper gives some ideas about how to use CAI effectively. Related Articles | Metrics

Select

Talking about self-learning of engineering graphics curriculum Wang Zhizhong 2012, 33(6): 121-123.  Abstract ( 74 )   PDF (190KB) ( 233 )   Independent learning is described as new revolution in modern education. Emphasizing the development of independent learning in university education is of great significance on cultivating creative talents. University education should build self-learning platform for students and teachers should focus on developing effective teaching methods and strategies to promote independent learning ability. This article makes a preliminary discussion on how to cultivate self-learning ability, how to improve teaching methods and strategies and how to reform independent learning environment in engineering graphics curriculum. Related Articles | Metrics

Select

Practice and reflection on enhancing students’ ability to interpret blueprints in the teaching of“3D mechanical drawing” Xu Dan 2012, 33(6): 124-130.  Abstract ( 89 )   PDF (448KB) ( 389 )   With 3D Solid Structure becoming the main expression and the expression of 3D design and 2D engineering graphics being equally important, teaching reform of knowledge structure system is deepening. More and more people begin to realize it and the amount of relevant papers is continuously increasing. This is because that, with the development of computer science and technology, computer technology has gradually spread into the fields of other sciences, having changed the structure of industries in the society, and, as one of the oldest subjects, engineering drawing is also meeting the revolution brought by the new technology era. So, in order to conform to the development of the times, it is the inevitable trend of the development of history that the expression of 3D by 2D projection transits to direct 3D design in graphics education. Based on the practical experience of teaching“3D mechanical drawing”for more than a decade, aiming at how to improve students’ spatial imagination ability and to finish the transit 2D to 3D, this paper summarizes the educational reform practice in these years as well as the author’s own teaching practice and reflection on it. Related Articles | Metrics

Select

Multi objective optimization based on dynamic incentives and elastohydrodynamic lubrication of gear Qian Xueyi, Wu Shuang 2012, 33(6): 130-135.  Abstract ( 69 )   PDF (404KB) ( 185 )   According to the fundamental of gear mesh dynamic incentives and elastohydrodynamic lubrication theory, this paper establishes a mathematical model of constraint multi objective optimization, which seeks the minimum of time-varying stiffness excitation of gear mesh, the maximum of minimum oil film thickness (the minimum reciprocal) in tooth space, and the minimum of total volume of transmission at the same time. This paper improves present particle swarm optimization of two- objective optimization and shows a design of constraint three-objective optimization. It also programs optimization by Matlab and analyzes examples. The optimization process and result show that, in less than one range, when more number of teeth, larger positive modification coefficient and appropriate pressure angle are adopted, the amplitude of fundamental harmonic in the tooth mesh spectrogram of synthetical stiffness is enlarged, and the capacity and cost performance are increased effectively while the gear powertrain system resists vibration of internal incentives. Related Articles | Metrics

Select

Method of wing surface shape error detection based on CAD Liu Zilu, Zhang Li, Zheng Guolei 2012, 33(6): 136-139.  Abstract ( 51 )   PDF (277KB) ( 251 )   Digitization error detection is one of the key technologies to insure the assembling quality of wing unit. A surface shape error detection method is given to get the wing surface quality data accurately. A fast algorithm has been studied to calculate the wing surface error, corresponding detection program is developed. The results show that the surface error of the wing surface shape can be acquired quickly and correctly, and a color drawing is displayed visually. Related Articles | Metrics

Select

A simple drawing method for two-point perspective in an ideal angle Qiu Bing, Zhang Fan 2012, 33(6): 140-145.  Abstract ( 64 )   PDF (381KB) ( 313 )   To resolve problems of perspective drawing in architecture design sketching, the paper presents a simplified method which is applied with ruler and compasses. Three special principles are generalized from the basic principle of perspective drawing as follows: selection of an ideal angle, drawing method with vanishing points outside drawing plate, and usage of sub measuring points. Based on the spatial relation of some auxiliary points and key points, this method gives play to the comprehensive functions of the three principles so as to simplify the drawing processes. The experimental results show that an ideal perspective drawing can be obtained in an easy manner without relying on the perspective point of drawing plane and visual angle. Related Articles | Metrics

Select

Process information identifying method based on model Zhang Xiangxiang, Chen Xingyu, Cheng Wusi, Zhang Hongqi, Zeng Xiangyu 2012, 33(6): 146-150.  Abstract ( 68 )   PDF (320KB) ( 279 )   To solve the problem of expressing process information based on the 3D model is a hot-point. An expression method for machining process information based on MBD and GB/T 24734-2009 is proposed. This method defines effectively the information sign and the combination sign, relating the process information and model by 3D annotation. It is showed that process model and information can be browsed directly. Based on the research, the method has been validated on the Pro/E platform and an example is presented. Related Articles | Metrics