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29 June 2012, Volume 33 Issue 3 Previous Issue    Next Issue

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Optimizing axonometric projection of an object on stereoscopic effect Xu Yueyue, Lin Dajun 2012, 33(3): 1-4.  Abstract ( 86 )   PDF (229KB) ( 198 )   The axonometric drawing has the advantages of good visualization and lifelike image. The stereoscopic effects of the axonometric drawing are relative to the position of the geometric object. The stereoscopic effects and improve the readability of graphics can be enhanced with the proper angle of view. According to the number of the visible planes in the drawing, and their size and change rate in area, influence acting on the stereoscopic effects can easily be revealed. By editing a human-computer interaction system using VisualLISP language which embedded in AutoCAD Software and VB Software, a basis is finally set on which axonometric projection can more efficiently express objects. Related Articles | Metrics

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Web-based aircraft assembly visualization system Liu Jian, Zhao Gang 2012, 33(3): 5-10.  Abstract ( 83 )   PDF (506KB) ( 221 )   Due to the low quality and efficiency, together with the disordered management during the aircraft’s assembly stage at present, an assembly process visualization system based on B/S structure is designed and implemented for the workshop. An information model of the plant based on the idea of single source of product data is constructed and several practical features are realized. Assembly processes are simulated using DELMIA solution and published in web pages which have the direct 3d interaction functionality by ActiveX, also authorized administration mechanisms are taken to make sure members of different roles are classified to have different privileges. In the end, a large aircraft's cabin door is used to verify the feasibility of the system. Related Articles | Metrics

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Improvement of task scheduling based on Q-learning Liu Xiaoping, Du Lin, Shi Hui 2012, 33(3): 11-16.  Abstract ( 118 )   PDF (224KB) ( 450 )   In this paper, a Markov Decision Process model is built to describe the problem of task scheduling in cooperative work, and a improved Q-learning algorithm based on Metropolis rule is present to solve the problem. In the algorithm, Metropolis rule combined with Greedy Strategy is introduced and a selection in state space is adopted, which accelerate the convergence, and shorten the running time. Finally, the algorithm is compared to some related algorithms of other papers, and the algorithm performance is analyzed as well, which indicates the efficiency of the improved Q-learning algorithm. Related Articles | Metrics

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Surface quadrilateral mesh generation based on Riemannian metric and its implementation in UG-NX Guo Xinqiang, Zhang Jianming, Qin Xianyun, Mu Donghui, Song Qiao 2012, 33(3): 17-23.  Abstract ( 83 )   PDF (344KB) ( 305 )   An improved paving algorithm based on the Riemannian metric is proposed for the mesh generation in the parametric surface. To obtain fine mesh in 3D space, the locations of the corresponding points in 2D parametric space are calculated using the Riemannian metric. Some improvements on the intersection disposal in the paving method are made. The improved method is implemented to generate quadrilateral mesh on surfaces of a solid model, which is constructed by UG-NX. In this implementation, geometric data of the solid model are obtained through functions from the function library in UG\OPEN API. Examples indicate that surface mesh with high quality can be generated by our method. Related Articles | Metrics

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Finite element analysis and experiment of big horsepower tractor drive axle Dong Yude, Yao Liangliang, Liu Zhen, Cao Wengang, Deng Lei, Wang Kailiang, Liu Yuezai 2012, 33(3): 24-28.  Abstract ( 127 )   PDF (480KB) ( 209 )   Drive axle sustains heavy force and is frequently used to transmit power and bear weight of the tractor. Security of design can be verified and improved by the result of the finite element analysis. First, hypermesh is used to proceed the preprocessing of the finite element analysis to axle housing, steering joint, half-axle model which is designed by Pro/E, ANSYS is used to proceed finite element analysis. By the result of the analysis and rigidity experiment, fatigue experiment to housing, the correctness of design can be verified, and some advices are given to increase the rigidity and fatigue lifetime for big horsepower tractor drive axle. Related Articles | Metrics

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An adaptive algorithm for rectangular packing problems Wang Jinmin, Wang Baochun, Zhu Yanhua 2012, 33(3): 29-33.  Abstract ( 95 )   PDF (254KB) ( 383 )   Rectangular packing problem is NP-Hard and normally solved by heuristic algorithms. By combining simulated annealing with genetic algorithm, an adaptive algorithm for rectangular packing problem is presented. The placement function for the structural algorithm is studied. Some strategies such as adaptive crossover, mutation and the probability of accepting poor solution can be used in order to optimize the parameter of placement function. The algorithm through two way determination initial population's number has the strong compatibility. In the algorithm search’s later period, the most different individual is used to carry on crossover operation, thus maintains the population’s multiplicity. The experimental results show that the algorithm is reasonable and efficient with comparing ones of other algorithms. Related Articles | Metrics

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A lossless simplifying method of and/or function tree Tang Yiming, Liu Xiaoping 2012, 33(3): 34-40.  Abstract ( 91 )   PDF (367KB) ( 192 )   Aiming at huge solving space and difficult conflict-orienting for large-scale function tree in conceptual design, a lossless simplifying method of and/or function tree is proposed. Some lossless simplifying theorems related to contract, deleting and extracting are proved, and then the lossless simplifying algorithm of and/or function tree is given based on these theorems. Finally, experimental results show that the algorithm can effectively reduce complexity holding logic equivalence and lossless innovative ability, and improve the efficiency of conceptual design. Related Articles | Metrics

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Mobile robot path planning based on improved genetic algorithm Wang Fenghong, Deng Zhiyan, Chen Chikun 2012, 33(3): 41-45.  Abstract ( 100 )   PDF (351KB) ( 253 )   The traditional genetic algorithm has the faults of slow evolving speed being easy to get into local optimum etc., an improved one based on it is provided. The improved one extends the barriers based on the principle of Minkowshi theory in the step of estimating the path and improves the graphic theory to construct the real feasible region. In the step of calculating the shortest path, population initialization individual coding method and so on are researched and the concept of similarity in the selection operator is imported which can enlarge the range of the early population and to avoid to get into the local optimum. At last, simulation test proves that the improved algorithm is feasible. Related Articles | Metrics

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A method for modeling leaves by deformation based on Laplacian coordinates Miao Teng, Zhao Chunjiang, Lu Shenglian, Guo Xinyu 2012, 33(3): 46-51.  Abstract ( 102 )   PDF (436KB) ( 192 )   This paper describes a realistic interactive method for modeling leaves by deformation based on Laplacian coordinates. This method generates the leaf meshes Using the silhouette and axial venation data of a leaf as input. The leaf surface can be edited interactively by using Laplacian coordinates as deformation calculation. The silhouette and axial venation data can be obtained using laser scanner or calculated by vein patterns. Experimental results show that the proposed method is very fast in deformation calculation and enough for real-time interactive application, with good universality. The generated 3D leaves model can not only maintain its area, but also show realistic effects. Related Articles | Metrics

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An interactive design system for special-shaped box Chen Jinchang, Li Ruolei 2012, 33(3): 52-55.  Abstract ( 67 )   PDF (294KB) ( 198 )   The design method of special-shaped box is provided by applying three-dimensional composition principle and treating papers as the objects, which make the design rule of special-shaped box can be fined. The interactive design system of special-shaped box is developed, and the function framework, design flow and the user interface of the system are analyzed. At last, an example is used to show the system’s utility. Related Articles | Metrics

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A collaborative design system for customized lighting based on Web3D Feng Kaiping, Pan Guangyang 2012, 33(3): 56-60.  Abstract ( 80 )   PDF (231KB) ( 383 )   The shortcoming of traditional design process of lighting is analyzed, and a practicable plan of collaborative design between customer and designer is presented. Crucial technology in the collaborative design of lighting based on Web3D is particularly described which includes how to achieve interaction, synchronization and mutual repellence in lighting design. And it developed an online design system based on web3d technology in which the customers play the host role while the designers play the consultant role. The system has been validated by experiment. Related Articles | Metrics

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Design of portable elliptical trainer Zhang Xiao, Huang Qiang 2012, 33(3): 61-64.  Abstract ( 135 )   PDF (346KB) ( 254 )   A novel portable elliptical trainer is invented. The motional properties and shortages of the existing products are introduced briefly. The design programs of this mechanism are analyzed based on the principles of ergonomics. Motion geometry analysis is carried out with a working model, and the three dimensional models is accomplished with the Pro/E software knowledge. It can be seen from the design results that the structure of the mechanism is very simple and flexible, and conveniently employed in different applications. Related Articles | Metrics

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A new high precision simulation method for MEMS comb actuator and the experiment Guo Zhanshe, Cao Le, Zhao Xin, Fan Shangchun 2012, 33(3): 65-68.  Abstract ( 59 )   PDF (303KB) ( 296 )   A new simulation method is introduced to solve the problem of high calculating errors of the ideal model caused by the edge effect for MEMS (Micro-electromechanical System) comb capacitor. In this method, the energy method in FEM (Finite Element Method) is used and the MEMS comb actuator (90 pairs of comb teeth) which is fabricated on a MEMS gyroscope is used for simulation. The simulated results of capacitance with this method and the conventional method CMATRIX are 1.5283pF and 1.5793pF. The relative errors between them and the LCR high precision capacitance measuring device measured result 1.5172pF are 0.73% and 4.09% respectively. It is concluded from the experiment this method can obtain high calculating precision for MEMS comb capacitor. Related Articles | Metrics

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Feature modeling of parts in collaborative virtual maintenance Ou Liming, Xu Xiaogang, Sun Yuanyuan 2012, 33(3): 69-72.  Abstract ( 76 )   PDF (464KB) ( 178 )   Collaborative virtual maintenance is that a team repairs large equipment in collaboration. The number of accessory is very huge and its relationship is complicated too. In allusion to solve the problem about how to organize and share the parts information, the information needed in the collaborative maintenance process is analyzed. The Object-oriented idea is adopted, and a parts feature model is set up composed of the maintenance sequence, the movement restriction, the personnel role and the maintenance tool. The parts feature model is finally mapped into relational data type, and stored in the database. An example of collaborative virtual maintenance of a certain type warship cannon is given. Related Articles | Metrics

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Real-time watercolor illustrations and animation on GPU Wang Miaoyi, Wang Bin, Yong Junhai 2012, 33(3): 73-80.  Abstract ( 79 )   PDF (5155KB) ( 339 )   This paper presents a real-time approach to render 3D scenes with the effects of watercolor on GPU. Most processes of the approach are implemented with image-space techniques. Our algorithm renders detail layer, ambient layer and stroke layer separately, and then combines them into final result. During the rendering processes, screen space ambient occlusion and shadow mapping are used to compute shadow in much shorter time, and image filter approach is used to simulate important effects of watercolor. Because our approach is mainly implemented with image-space techniques, it is convenient to use GPU to accelerate the rendering processes and finally our approach achieves real-time speed. A system is also setup to play scripts and output real-time animation, which indicates that this approach can be extended to diverse applications such as computer animation, game and other multimedia entertainment industries. Related Articles | Metrics

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Envelope analysis for dynamic simulation of automobile powertrain Hu Ning, Yin Penghe, Gao Weimin, Xu Kangcong 2012, 33(3): 81-84.  Abstract ( 95 )   PDF (392KB) ( 298 )   In order to layout powertrain in a space-limited engine cabin reasonably, it is required to determine powertrain dynamic envelope. Both conversion of powertrain mathematic model and simplification of envelope-analog under all circumstances could be realized by using coordinate transformation and special points extraction. The research aided by CAA, the secondary development tool of CATIA, is trying to produce an analyzing module which can stimulate powertrain dynamic envelope to simplify its data, reduce calculating time and improve efficiency. Related Articles | Metrics

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Virtual exhibition and customization based on Web3D Wu Yanfang 2012, 33(3): 85-89.  Abstract ( 82 )   PDF (451KB) ( 169 )   This paper aims at the specialties of virtual exhibition and customization. Some technologies and design tools are analyzed, and a general method for dynamic interactive browse and customization on Web is proposed. Based on development environment of cult3d, customizing color and form of 3D models and dynamic browse are realized by using interrelated actions, events and JAS. In order to improve the convenience of operation, the triggering manual events and optimizing interface are achieved by media mixing, in the meanwhile, a system of exhibition and customization about mobile is developed based on Web3D technology. Related Articles | Metrics

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A 3D rapid assembly design method for embedded part of industrial building Du Linbao, Huang Xueliang, Wang Yanwei, Chen Gang, Chen Liping 2012, 33(3): 90-96.  Abstract ( 84 )   PDF (291KB) ( 186 )   Currently, embed-parts design of industrial building structure always makes use of 2D CAD software, which is proven to be inefficient and error-prone. A generalized parametric template based on assemble design method is proposed to improve the design efficiency and quality. In this method, the generalized parametric template is established which encapsulates 3D parametric structure, assembly constraint information and 2D schematic diagram, etc.. Then, the library of parametric template of embed-parts is developed. Based on that, a history-based assembly design technique is employed to assemble the embed-parts efficiently in three dimension design environment. The proposed method has been implemented in the commercial 3D CAD software for industrial building structure called InteRDS, which has been applied in practical engineering design. Related Articles | Metrics

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Rapid moving object detection under a rotating camera Jiang Jianguo,Wu Hui, Qi Meibin, Zhang Li 2012, 33(3): 97-101.  Abstract ( 86 )   PDF (267KB) ( 178 )   This paper proposed a algorithm for detecting moving object based on camera rotation motion. First, the rotational parameter models are built for global motion images. Secondly, SIFT point pairs are established based on motion prediction between successive frames and RANSAC algorithm is used to eliminate the outliers. With the least square method precisely computing the motion compensation, an updating strategy based on residual image, which updates the feature point set sequentially, can adjust the change of the background. Finally, motion object is detected by Frame difference method. This novel algorithm remains the advantages of SIFT and raises the detection rate significantly. The experiment results demonstrate that this algorithm can effectively detect objects while achieving real-time performance. Related Articles | Metrics

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A recognition iris method based on kernel principal component analysis and two-layer serial classifier Wu Youfu 2012, 33(3): 102-106.  Abstract ( 89 )   PDF (326KB) ( 170 )   A new method for the iris feature extraction and recognition was proposed in this paper. Firstly, the kernel principal component analysis (KPCA) was used to extract texture features of iris image because which has the strong ability to extract features in high dimensions space. In order to reduce the samples of the support venture machine (SVM), the two-layer serial classifier was designed which combined SVM and distance classification, a rejecting coefficient and rejecting rule were defined. According to the rejecting rule, the distance classifier could classify the iris images and give the final results, or reject to classify. The rejected iris images were fed into SVM for further classification. The classification algorithms could take advantage of SVM and distance classification. The experimental results show that the method can improve the rate of iris recognition, and is effective. Related Articles | Metrics

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The publication practice on bilingual text books for engineering graphics Zhuang Hongquan 2012, 33(3): 107-109.  Abstract ( 112 )   PDF (142KB) ( 218 )   In recent years, bilingual teaching has attracted a lot of attentions in engineering graphics teaching reformation. The bilingual text books for the engineering graphics are important to the reformation. The bilingual text books for engineering graphics in China are discussed. The publication and characteristics of the engineering graphics series were introduced. Related Articles | Metrics

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Training students' innovative design and practice ability in engineering drawing course Wu Qifeng 2012, 33(3): 110-117.  Abstract ( 71 )   PDF (252KB) ( 227 )   Aimed at the problem training students’ expression ability，innovation design ability and practice ability in engineering drawing course, both basic theory and application of methods are needed in order to guide students to correctly analyze problem by using of the projective rules and discover new relative ones. The results in teaching and engineering practice show that training the basic theory is very important. The basic thinking way of the expression in engineering drawing is proposed which students must be trained. The teaching difficulties and focus in engineering drawing course are determined based on the training results of students’ innovation design and practice ability. Related Articles | Metrics

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The drawing method for structure of a part after cutting plane Tian Junying 2012, 33(3): 117-119.  Abstract ( 59 )   PDF (195KB) ( 202 )   Based on the drawing method of structure of a part after a cutting pane in cutaway view in mechanical drawing standard, the specific definition of “other structures after the cutting plane” and “Sectioning structure and its related parts” is established. If the axis of physique which it belongs to is intersection of two section cutting plane when some structures have not been split cut, it is the other structures after the cutting plane, and it should be projected according to the original position. Otherwise, it is the sectioning structure and its related parts, and should be rotated to a new location with his structure. This paper also describes with proven that it should not delete “the other structures behind a cutting plane are projected according to the original location” in mechanical drawing standard. Related Articles | Metrics

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Software for auto-generation testpaper of mechanical courses based on CAXA Dai Meiquan 2012, 33(3): 120-124.  Abstract ( 87 )   PDF (192KB) ( 220 )   According to the present situation and the actual demand for the testpaper database system of mechanical courses, some key technologies such as secondary development of CAXA program, algorithm of auto-generation testpaper, as well as tips of intelligent typesetting are researched, and then a software for testpaper auto-generation of mechanical courses is designed and realized, which is seamless integrated into CAXA and convenient to use. There is certain reference value for the development of the same kind computer aided teaching software. Related Articles | Metrics

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The inversion between Mandelbrot and Julia sets Li Jinfei, Sheng Zhongping 2012, 33(3): 125-128.  Abstract ( 89 )   PDF (328KB) ( 183 )   The inversion problem between Mandelbrot and Julia sets is discussed in this paper. Providing the inversions of arbitrary point on extended complex plane to iterative functions, it obtains two kinds of conjugate function of the iterative function drawing Julia and Mandelbrot sets. The Julia and Mandelbrot sets for the two kinds of conjugate function, are exactly the inversion figures of original ones. Using the escape time algorithm, it draws the inversion figures of Julia and Mandelbrot sets. Related Articles | Metrics

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Wind turbine sequence modeling based on secondary parametric technology Gao Qingfeng, Sun Zhengxing, Teng Wei, Liu Yibing 2012, 33(3): 129-134.  Abstract ( 102 )   PDF (935KB) ( 229 )   According to the disadvantages of conventional modeling methods for large and complex wind turbines, a highly efficient modeling method is proposed in this paper. Based on a fully parametric model of a single wind turbine, it took the whole sequence of wind turbines as the research object, and realized the fast modeling via secondary parametric technology according to the change law of design parameters of different wind turbines in the same sequence. A sequence modeling system for wind turbines was also developed by combining with parameter-driven modeling technology. The system can effectively reduce the workload and design error rate, improve design efficiency, and prove the correctness and rationality of the modeling method. Related Articles | Metrics