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28 October 2011, Volume 32 Issue 5 Previous Issue    Next Issue

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Bridge Parametric Modeling Based on Knowledge CHEN Ming, HU Shi-de 2011, 32(5): 1-9.  Abstract ( 68 )   PDF (524KB) ( 340 )   In this paper, parametric modeling based on knowledge is presented, whichconsist of the knowledge presentation model in bridge design, the method of knowledge acquistion (KA), the algorithm of bridge structure composition and the algorithm of bridge intelligent changing. The results of the study are validated through a seismic analysis where a 6×70m pre-stressed concrete continuous bridge is used. Comparison between traditional method and parametric method based on knowledge shows that parametric method based on knowledge is more effective in bridge modeling, especially in complex modeling to be modified frequently. Related Articles | Metrics

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Reliability Optimization Design and Solid Modeling of Cylinder Gear Speed Reducer GONG Xiao-ping, JIANG Juan-na, LIU Yi-jing 2011, 32(5): 10-15.  Abstract ( 100 )   PDF (613KB) ( 225 )   Taking the randomness of the stress and strength into consideration, regarding the given reliabilities of the tooth contact and the root bending fatigue strength as constraints and applying the mechanical optimization design theory, a multi-objective reliability optimization model of single-grade helical gear speed reducer is built to determine the parameters of the gear mechanism. The solid model of the gear speed reducer is established by the SolidWorks software and its motion simulation is realized by the COSMOSMotion plug-in, which provides a practical and feasible approach to design the gear speed reducers by the computer-aided method. Related Articles | Metrics

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The Development of Elliptic Pipe on Ellipsoidal Head WANG Jin-min, WANG Ai 2011, 32(5): 16-19.  Abstract ( 81 )   PDF (614KB) ( 184 )   Using the method of mathematical analysis and geometrical theory, the paper introduces the mathematical models about ellipsoidal head and elliptic pipe. The developed equation of the elliptic pipe on ellipsoidal head is derived, and general program for development of elliptic pipe is given. Finally, some examples are given to indicate that the method is simple and convenient in practical use. Related Articles | Metrics

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Two New Extensions of Cubic Ball Curve YAN Lan-lan, LIANG Jiong-feng, RAO Zhi-yong 2011, 32(5): 20-24.  Abstract ( 66 )   PDF (457KB) ( 207 )   Two classes of polynomial basis of 3th and 4th degree are presented. They are extensions of cubic Ball basis. Based on these two bases, two polynomial curves with shape parameters are defined. They not only inherit the outstanding properties of the cubic Ball curve, but also are adjustable in shape and fit closer to the control polygon than the cubic Ball curve. The geometrical meaning of shape parameters is discovered by analyzing the connection of the new curves and the Bézier curve. Meanwhile, the geometrical drawing method of the extension curves is given out. Related Articles | Metrics

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An Otsu Dual-threshold Value Method Based on Simulated Annealing Parallel Genetic Algorithm for Medical Image Segmentation XU Liang-feng, LIN Hui, HU Min, WU Dong-sheng, XU Yuan-ying, JING Jia 2011, 32(5): 25-29.  Abstract ( 138 )   PDF (482KB) ( 218 )   Simulated annealing and parallel genetic algorithm are two helpful methods which can improve the performance of evolutionary algorithm. The paper applies the global optimum performance of evolutionary programming and the hill climbing performance of simulated annealing, and proposes an Otsu dual-threshold value method based on simulated annealing parallel genetic algorithm for medical image segmentation. In the algorithm, evolutions of subgroups are performed among subgroups in parallel, and the hill climbing performance of simulated annealing is utilized, so this algorithm avoids premature convergence of alone group evolutionary process and improves its convergence efficiency. Experiments show that this new algorithm can achieve exact image segmentation and is of better accuracy and stability than parallel genetic algorithm, and its convergence speed is faster than the Otsu dual-threshold value method based on parallel genetic algorithm. Related Articles | Metrics

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A Digital Watermarking Algorithm Based on SVD WANG Hui-qin, WANG Jia-lu WANG Ke1 QI Hai-ping 2011, 32(5): 30-34.  Abstract ( 103 )   PDF (528KB) ( 208 )   In this paper, an adaptive watermarking algorithm of image based on Singular Value Decomposition (SVD) is proposed. Binary barcode is taken as watermarking embedded into the S component of SVD. By exploiting the visual masking and texture characteristics of Human Visual System (HVS), the strength of embedded watermarks is decided by the gray and texture of the original image. It ensures the self-adaptation of the intention of the embedded watermarks to the original image. The watermarked image is adjusted by using Radon transform before the watermarking is extracted and then the extracting barcode is corrected according to the characters of itself. The experimental results show that the proposed algorithm is invisible and robust against many commonly used image-processing methods and especially against geometric attack. This technology will be of good application in printing security. Related Articles | Metrics

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Research on Behavior Model of Virtual Dragoman LUO Yue-tong, SUN Jing, CHEN Tao 2011, 32(5): 35-39.  Abstract ( 79 )   PDF (397KB) ( 212 )   Behavior model is one of key parts of virtual dragoman. The paper studies virtual dragoman’s behavior model based on features of dragoman’s behavior, and presents a behavior model consisting of perception machine, domain knowledge database and reasoning machine. Perception machine perceives environment, dragoman’s behavior rules are recorded in domain-knowledge database, and based on which reasoning machine performs behavior reasoning. The paper introduces the concept, the principle and the structure of perception machine, domain knowledge database and reasoning machine; and the method’s application in “Real-time roaming system of the ancient San He town” is also shown. Related Articles | Metrics

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The Roaming and Interaction Technology of Virtual Campus Based on VRML FENG Gui-zhen, CHI Jian-bin, WANG Da-ming, ZHANG De-ying 2011, 32(5): 40-45.  Abstract ( 74 )   PDF (1008KB) ( 225 )   In view of the importance of the virtual campus on constructing the digital and information university, the roaming and interactive technology of VRML are studied with Shijiazhuang railway institute as an example. Building the scene with VRML and 3DMax, taking JavaScript as the programming tools of VRML SAI and EAI, the virtual campus system is implemented through the integration of VRML and HTML. The system has the functions of roaming, interactively manipulating the objects and searching the related message. The system visually displays the landscape and facilities of campus, provides convenience for consumers to inquire information, and is of good effect. Related Articles | Metrics

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A Novel Algorithm of Clued KD-tree on SIMD Architecture JIAO Liang-bao, CHEN Rui, ZHANG Jian 2011, 32(5): 46-50.  Abstract ( 80 )   PDF (407KB) ( 253 )   KD-tree is a traditional accelerating algorithm in 3D scene rendering, and its parallel processing performance is restricted to the unsupported recursion operations on SIMD architecture. A novel parallel algorithm is proposed to speed up KD-tree traversal on GPU. Clues pointing to six-direction subsequent nodes are inserted into the KD-tree structure. Thus, the algorithm efficiency is improved by avoiding stack data structure and reducing the worthless operations. The experiment results verify that the clued KD-tree algorithm increases the rendering speed by 3 to 8 times than the traditional algorithms. Related Articles | Metrics

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Research and Practice on Chinese-Japanese Bilingual Teaching of Mechanical Drawing Course SHU Hong, HU Qing-ni, GAO Fei 2011, 32(5): 51-55.  Abstract ( 75 )   PDF (497KB) ( 236 )   For the practice of Chinese-Japanese bilingual teaching course in mechanical drawing, several aspects in the textbook system construction and teaching practice method are analyzed, bilingual teaching features and their relationship in the teaching effect are discussed. Based on the practice of bilingual teaching, the teaching effect is analyzed through the results from questionnaire, and several questions and their solutions for the course are stated for the aim of engineering diathesis and capacity training. Related Articles | Metrics

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Teaching Reform of Engineering Graphics Based on CDIO GUO Chang-hong, ZHAO Bing-li, LI Xing-dong, JIANG Gui-rong 2011, 32(5): 56-60.  Abstract ( 69 )   PDF (408KB) ( 165 )   CDIO is a new pattern of current higher education, aiming at cultivating international engineers. The defects of current engineering graphics education and the thought of CDIO are introduced in the paper. A series of teaching reforms of engineering graphics based on CDIO have been put forward according to CDIO reform experiences in Yanshan University. The practice shows that such teaching model is very effective to inspire and cultivate practical ability and creativity of students. Meanwhile, it has also laid a good foundation for the follow-up courses, graduation design, even future research work. Related Articles | Metrics

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Design and Practice of the Research-Oriented Teaching Model in the Course of “Civil Engineering Drawing” KUANG Ming, LI Xue-mei, GAO Yue 2011, 32(5): 61-64.  Abstract ( 105 )   PDF (748KB) ( 272 )   The paper reviews the design and practice of the research-oriented teaching model in the course of civil engineering drawing. The teaching practice of the “housing construction drawing” is selected as an example of the application of this model. Task-driven approach is adopted in the teaching design in order to adapt to the characteristics of students. The focus is put on several major links such as the classroom teaching, instruction and training after class in the teaching design so as to guide the students to conduct research-oriented study. Students’ work is roundly evaluated from their standard, content, dimensioning, symbolic expression, written style and general aspects of the drawings. Teaching practice shows that this model can mobilize students' enthusiasm, expand their knowledge, and develop their engineering quality and team cooperation spirit, and at the same time, drawing quality is improved obviously and good teaching effect is achieved. Related Articles | Metrics

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Teaching Practice of Engineering Graphics Based on Constructivism Learning Theory ZHANG Bao-qing, SUN Li-hua, WU Xing 2011, 32(5): 65-68.  Abstract ( 101 )   PDF (392KB) ( 191 )   This paper elaborates the constructivism learning theory and some new teaching methods under its guidance. The integration of two- and three-dimension teaching of engineering graphics is taken as a breach of teaching reform. The teaching practice of engineering graphics in application of this model proves to be successful and achieves good effect. The summarization of the general practice program under the guidance of constructivism learning theory offers a new perspective of applying the theory to conduct teaching reform. Related Articles | Metrics

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An Optimization Strategy of Tool-path for 5-axis High-speed Machining Based on STL Modeling SUN Quan-ping, CHEN Qian-liang 2011, 32(5): 69-73.  Abstract ( 91 )   PDF (466KB) ( 192 )   Aiming at the linear-interpolation shortage of tangency discontinuities and too many interpolation-points along tool paths, an optimization strategy of tool path is presented for 5-axis high speed machining prostheses based on stereo lithography modeling. In this strategy, unnecessary interpolation points are removed, consequently all the tool paths are simplified; the surface of envelope cutter orientation is smoothed by adopting the advantages of ruled surface; a new method of spline interpolation is put forward to support Heidenhein CNC system. On the basis of these, G-codes generated by linear-interpolation are successfully transformed into Spline-codes. Using Vericut NC simulator, molar crown prostheses are manufactured. The test results show that the profits of the optimization strategy concern the reduction of machining time as well as the quality of the machined parts compared to those of linear-interpolation. Indeed, the tool-path continuity avoids the appearance of marks and facets. Related Articles | Metrics

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An Efficient Line Clipping Algorithm Against Circular Window REN Hong-hai, ZHANG Fei-xia 2011, 32(5): 74-78.  Abstract ( 81 )   PDF (388KB) ( 220 )   The result of clipping is discussed according to possible positions for both endpoints of a line segment in relation to circular window. The intersection is determined by comparing the slope of the tangent with the slope of the line segment and the ingenious region detection about the point when both endpoints of the line segment are outside of the circular window. Simplify the intersection equation by means of the intersection calculation with the parametric form when the intersection actually happens. The experimental results show that the new algorithm further improves the clipping efficiency. Related Articles | Metrics