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27 February 2013, Volume 34 Issue 1 Previous Issue    Next Issue

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A method for suppressing motion artifacts in IVUS image sequence Sun Zheng 2013, 34(1): 1-8.  Abstract ( 102 )   PDF (627KB) ( 194 )   A method for suppressing motion artifacts due to cyclic cardiac motion existing in continuous pullback coronary artery intravascular ultrasound (IVUS) image sequence acquired in vivo is proposed. Firstly, rigid motion parameters of cross-sectional vessel wall in tomographic image sequence are quantitatively estimated based on comprehensive analysis of both mechanism and expressions of motion artifacts. Then, dynamic and geometrical components of rigid motion parameters are separated with spectrum analysis technique. Finally, geometrical components of vessel wall motion in successive tomographic frames are quantitatively compensated to implement suppression of motion artifacts. Neither special ECG-gating acquisition device nor ECG signals are required. It is not required to discard useful frames to guarantee the integrity of the image data set. The validity has been demonstrated with computer-simulated and clinically acquired image data. Related Articles | Metrics

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Approximating ellipse using four-arcs with the smallest error Zeng Zhenbing, Chen Liangyu, Li Zhibin, Chen Guangxi 2013, 34(1): 9-16.  Abstract ( 142 )   PDF (357KB) ( 292 )   The distance of equidistant curves is used to estimate the errors between an ellipse and the four-arcs which approximate the ellipse. An explicit expression of the errors and the semi-axes of the ellipse are established. A new method is proposed for approximating an ellipse by using of four-arcs with minimal error via symbolic computation and regression analysis. Our method is easy for drawing with ruler and compass and can be used in interpolation programming for the computerized Numerical Control lathes. Related Articles | Metrics

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Automatic generation of Xinjiang ethnic fabric patterns based on configuration style Zhao Haiying, Pan Zhigeng, Xu Zhengguang 2013, 34(1): 17-21.  Abstract ( 70 )   PDF (501KB) ( 218 )   The Xinjiang ethnic fabric patterns are select as the study object. By analyzing their features, some rules are found that certain elements are repeated permutations and combinations. It is summarized into six tiles, which are hexagonal structure tile, brick-shaped structure tile, word structure tile, triangular tile, and diamond structure tile by decomposing these elements into basic configuration. During the creation process, the user first picks up a basic configuration, and then designs or embeds primitive pattern to fill the space inside the configuration. Finally, by folding or rotating extension generated a beautiful symmetrical pattern. Potential applications of the system are the design of Xinjiang Ethnic fabric pattern, advertisement and costume design field. Related Articles | Metrics

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A novel color edge detection based on robustness of cell neural network Jiang Qingling 2013, 34(1): 22-30.  Abstract ( 104 )   PDF (563KB) ( 238 )   Based on the cellular neutral network(CNN) mathematical model, a new method of color image edge detection is proposed. It inherits the advantages of CNN, and fills up a gap that the existing algorithms cannot directly detect the color image edge. This method takes advantage of the color information in the image to measure the differences between pixel by the Euclidean distance, allowing the CNN equation for operation in RGB color space. To make a theoretical analysis and robustness research for CNN template, a CNN robustness theorem is proposed that achieves the functional requirements of the color image edge detection, and provides the analytical criteria for designing the corresponding CNN templates parameters. The experimental results show that this algorithm is effective for the color image edge extraction. A quantitative evaluation validates the advantages of the accurate edge detection positioning. Related Articles | Metrics

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Lossless simplifying strategies of and/or/not function tree Tang Yiming, Liu Xiaoping 2013, 34(1): 31-40.  Abstract ( 129 )   PDF (610KB) ( 179 )   For large-scale and/or/not function trees in product conceptual design, it is usual to use logic simplifying to cut down redundancy; however logic simplifying may result in the loss of innovative ability. Aiming at this problem, the lossless simplifying strategies are proposed for and/or/not function trees. First of all, the strict definition of lossless simplifying of and/or/not function tree is given, and then the converting method from the and/or/not function tree to AND/OR tree is established. Moreover, some lossless simplifying theorems for the AND/OR tree are proved, and based on them the lossless simplifying algorithm of and/or/not function tree is obtained. Lastly, experimental results show that such strategies can effectively reduce computational cost under the condition to ensure logic equivalence and also lossless innovative ability, thus improve the efficiency of innovative reasoning. Related Articles | Metrics

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Extension of quartic Bézier curve with two shape parameters Liu Xiaoqiong，Yang Guoying 2013, 34(1): 41-45.  Abstract ( 70 )   PDF (333KB) ( 197 )   Two classes of six degree polynomial basis functions with two shape control parameters λ and μ are presented. They are extensions of quartic Bernstein basis functions. Properties of these two bases are analyzed and the corresponding polynomial curves with two parameters λ and μ are defined accordingly. These curves not only inherit the outstanding properties of quartic Bézier curve, but also can be adjusted in shape by changing the value of λ and μ without the changing of control points. The parameters have obvious geometric meaning. When λ =μ =0, the curve degenerates to four degree Bézier curve. Experiments show that the method given in this paper is intuitive, effective and easy to control. Related Articles | Metrics

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The generating algorithm of Voronoi after adding and deleting points Zhang Juan, Du Quanye 2013, 34(1): 46-49.  Abstract ( 85 )   PDF (191KB) ( 265 )   Voronoi is also called Thiessen polygon, which is a continuous polygon made of perpendicular bisectors by joining the two adjacent points. It is widely used in pattern recognition, computer graphics, computer aided design, geography information system and many other fields. A new approach of constructing TIN that represented terrain well was given based on Voronoi diagrams and Delaunay triangulation networks. It is easily to make full use of the management and loading of TIN in the establishment of DEM. The method of online incremental and reducing algorithm to realize the generation of Voronoi after adding and deleting points can change points actively, and it holds the superiorities of fast speed and high efficiency. Related Articles | Metrics

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Analytic expression method of airfoil profile shape based on a mean camber and thickness function Jiang Haibo, Zhao Yunpeng 2013, 34(1): 50-54.  Abstract ( 88 )   PDF (350KB) ( 202 )   It is important that the geometric shape of a complex airfoil contour be expressed by an analytic formula. In this paper, the method to construct airfoil contour by analytic functions is discussed. Joukowsky airfoil contour function is simplified to a straightforward expression with mean camber function and thickness function. Many airfoil contours can be constructed by redefining and transforming the coefficients and indexes in the expansion, and more complex airfoil contours can be obtained through separating and resetting the upper and lower contours. Also, the contour function of any airfoil with smooth trailing edge is obtained by adding an independent thickness function. It is shown that a complex airfoil contour can be expressed by an analytic function with limited parameters which have clear geometric meaning, and can be used to adjust the local shape easily. As an example of application, the paper also gives a method to construct analytic function of blade with an airfoil contour, a chord and a twist functions. Related Articles | Metrics

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Aircraft assembly tolerance information model based on assembly sequence Hong Jiansheng, Li Yingguang, Song Wenjuan, Wang Lei 2013, 34(1): 55-59.  Abstract ( 84 )   PDF (313KB) ( 195 )   The assembly tolerance representation model based on assembly sequence is proposed. In order to construct the assembly tolerance information model, the assembly parts’ related characteristics and the parts’ key characteristics are figured out, and all the processes are based on the assembly simulation sequence. This model considers the process of accumulated assembly tolerance which is affected by assembly sequence. This method decreases the complicated interactive operation in the artificial tolerance information modeling. In addition, it improves the quality of the assembly tolerance representation model. An aircraft assembly simulation system has been developed based on DELMIA and successfully deployed in aircraft assembly simulation in the engineering practice. Related Articles | Metrics

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Aircraft assembly task scheduling based on improved discrete particle swarm optimization Han Pengfei, Sun Zhanlei, Zhao Gang 2013, 34(1): 60-65.  Abstract ( 72 )   PDF (316KB) ( 225 )   The importance of task scheduling in aircraft assembly process and the current research status of scheduling algorithm is introduced. The discrete particle swarm optimization is analyzed, and an improvement of the algorithm based on self motivation principle is proposed. The improved algorithm has been well verified by the actual assembly process of an aircraft’s tail section. Related Articles | Metrics

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Three-phase numerical simulation of oxygen jet impinging on molten steel bath in EAF Chen Shaochun, Li Jingshe, Zhu Rong, He Chunlai 2013, 34(1): 66-70.  Abstract ( 129 )   PDF (705KB) ( 191 )   By Fluent 6.3, this paper develops a mathematical model of three-dimensional and three-phase flow in the molten bath of EAF with side accessorial oxygen lance to study the transient phenomena of jet impingement on molten steel. The simulation result shows that the impingement of the supersonic oxygen jet will cause impact dent on the molten steel surface, will inspire wave of the molten bath surface from the dent centre to the bath center, and will cause vortexes under bath which become the centre of molten steel circumfluence. The velocity of flowing molten steel under the oxygen lance or around furnace wall will be faster than that at the center of bath. With oxygen jet enhance, the center of vortexes will be more apart from the impingement point of jet and will be lower to the bottom of bath. The area of impact dent S (m2) is almost in linear relationship with flow rate of jet QO2 (m3/h), in direct proportion. After consulting, the relationship between the area of impact dent and flow rate of jet can be expressed by the following mathematical equation: 2 0.0004 * 0.0932 . Related Articles | Metrics

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Developing engineering drawing module base on ObjectARX Wei Yongle, Chao Caixia 2013, 34(1): 71-76.  Abstract ( 141 )   PDF (213KB) ( 232 )   The 3D solid modeling is used widely in the design of machine production. But, the 2D drawing is still essential in production manufacturing and in technical exchanging. In order to construct the 2D drawing from 3D solid model, the engineering drawing module is developed based on AutoCAD with the secondary development tool ObjcetARX. Constructing the 2D drawing from a 3D solid model and automatic dimension are realized, and the 2D drawing is created in the model space which makes the user’s operation more convenient. An example shows that the engineering drawing module can extract the information of the 2D drawing from the 3D features solid and can construct 2D drawing rapidly. The design efficiency can be enhanced greatly. Related Articles | Metrics

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Application of CAD technology in mine and geology Yang Gang, Li Yingfeng 2013, 34(1): 77-82.  Abstract ( 83 )   PDF (261KB) ( 199 )   Mine geological condition is complicated. It can enhance the intelligentization of mine design to adopt CAD. Some questions are studied, such as the method to draw the section lines in the geological section plane and the geological plane graph intersected each other, the principle and method of automatic determining ore body limits on transverse section by using of the neural network theory, the one of drawing the slippery boundary of ore, and the method of automatic calculation and statistics ore reserves and grade. A mine CAD system was exploited with ObjectARX based on these methods. The experiment shows it is feasible and successful after it was used in Beiminghe iron mine. Related Articles | Metrics

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The library of virtual model of engineering graphics based on smart phone Qiu Longhui, Chu Dianming, Ye Lin 2013, 34(1): 83-86.  Abstract ( 88 )   PDF (248KB) ( 181 )   A virtual model library of engineering graphics is established to solve the problem of the time and space limit to the use of existing virtual model library. The model library system structure is designed, the mobile device operating system is analyzed, and the development and operation platform of the virtual model library is determined. Based on the analysis of the primitive drawing method of the class of Mesh, its data needs and VRML97 data format, the document analytical class of VRML is designed. The 3D browser of VRML model is designed on the mobile device. The virtual model library of engineering graphics based on mobile device is realized. The system improves the practicability of the virtual model library, successfully expand space and time in use of the virtual model. Related Articles | Metrics

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The motion simulation of high-speed train Lü Xikui, ZhouXiaoping, Jia Xiaoqiu 2013, 34(1): 87-91.  Abstract ( 90 )   PDF (422KB) ( 270 )   The three-dimensional dynamic simulation model based on varying parameters is established for the CRH high-speed train, and the real-time transfer and assembly of various train element models during the process of motion are achieved. A high-speed train movement simulation system is developed using Visual C++ 6.0, OpenGL 3D graphics library and the Oracle Database. A comprehensive integrated simulation system between High-speed train movement and three-dimensional line design is established. The experiments show that good simulation results are obtained. Related Articles | Metrics

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Motion simulation of clean algae machine based on multi-joint inverse kinematics Yang Guang, Chen Zhuping, Xiao Wei 2013, 34(1): 92-95.  Abstract ( 77 )   PDF (429KB) ( 191 )   Water pollution caused by algae, water lettuce and other aquatic plants has led to environmental damage. The movement process of small mechanical devices is studied based on multi-joint inverse kinematics (IK). System's three dimensional modeling is established by using of the CAXA program. Based on the optimization and date exchange, the lever link of salvage device parts is established using 3ds max software. The IK algorithm is used in motion simulation and trajectory analysis. The movement of salvage device, position trajectory of IK chain and movement trajectory of harrow claw are obtained. The method is suitable for high interactivity and real-time applications such as movement trajectory design, motion editing and optimization. Related Articles | Metrics

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Workflow change among enterprises based on VPDM Liang Keshan, Tang Li, Cao Yujun, Cheng Chen 2013, 34(1): 96-100.  Abstract ( 69 )   PDF (293KB) ( 168 )   Workflow change is an important problem that often needs addressed in enterprise business process, especially the cooperation in cross-enterprises. Contraposing that most enterprises have widely applied PDM system, this paper proposes a VPDM(Virtual PDM) method to solve workflow change among enterprises. Its realization mechanism is described, the processing method and the procedure about the VPDM-based workflow change are both given elaborate discussion, which is divided into two types, i.e. up to down change as well as down to up change, and their dealing processes are presented, respectively. After that, ignorable activities are described and a recursion judgment algorithm on them is introduced. A successful example verifies feasibility of developed software on solving the problem of the change of workflows during some sort of product’s research process. Related Articles | Metrics

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A dynamic interactive simulation system for shield machine Feng Guizhen, Chi Jianbin, Zhangzengqiang, Wang Chen 2013, 34(1): 101-104.  Abstract ( 110 )   PDF (285KB) ( 169 )   A shield machine is a kind of special engineering equipment which is used for underground construction such as tunnel excavation. For the high complexity of the tunneling equipment, the security problems are taken due to the uncertainties of geological and working conditions. A web-based interactive assembly, motion simulation and virtual roaming system is developed with VRML, Cult3D, HTML, etc., which has the functions of navigation roaming, interactively manipulating virtual object, information inquiries, and so on. It can visually show the construction and principles of shield machine, and provide a good platform for operating the shield machine. Related Articles | Metrics

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Exploration and practice for design ability based on shape configuration in engineering drawing Chen Jinchang, Chen Liang, Zhang Ruiqiu, Chen Chikun 2013, 34(1): 105-110.  Abstract ( 106 )   PDF (443KB) ( 319 )   Developing student innovation ability and engineering consciousness is the main purpose of shape configuration. This paper presents the curriculum system based on shape configuration design for engineering course, and analyzes some training styles for shape configuration design. An effective training method, small product design, is introduced in teaching process for engineering drawing course. The assignment, implement and examination of small product design are discussed in detail. The results of practice application show that introducing small product design has a meaning for engineering graphics teaching reform. Related Articles | Metrics

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The CAD skills competition and the situation analysis of CAD education in China Deng Xuexiong, Xiong Zhiyong, Liu Lin, Xiong Wei 2013, 34(1): 111-115.  Abstract ( 86 )   PDF (235KB) ( 233 )   The Mechanical Engineering Design – CAD project of Worldskills International competition and the CAD skills competition in Guangdong province for the last two years is introduced and analyzed. Based on this, the problem of how to introduce the standards and rules of the Worldskills International Competition into CAD skills competition in Guangdong province is deeply studied. Then, the situation of mechanical CAD in China is stated from three aspects in the follows: the current application of CAD in enterprises, teaching of CAD in the schools and professional qualification examination of CAD. Finally, the current schools education of mechanical design course, mechanical drawing course and CAD course in China and abroad are studied, and the gap between them as well as the problems which should be taken seriously are presented. Related Articles | Metrics

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Practice in the form of engineering drawing and mapping Yang Li, Hao Yuxin, Wang Jianhua 2013, 34(1): 116-119.  Abstract ( 119 )   PDF (175KB) ( 317 )   Engineering drawing and mapping is a basic part in practice teaching. This paper discusses the computer auxiliary mapping system developed by ourselves, the project teaching method, and the project management and examination system introduced in practice teaching. All these can help release the contradiction between less teaching hours and more work of drawing and arouse students’ interests of learning. It is a good way to improve their comprehensive quality and spirit of exploration and innovation. Related Articles | Metrics

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Probing into the teaching methods of engineering drawing Lan Xiaomin, Wang Shengzhi 2013, 34(1): 120-121.  Abstract ( 58 )   PDF (159KB) ( 169 )   This paper analyzes the advantages and problems of the commonly adopted multimedia teaching between students and teachers, between traditional and multimedia teaching. The advantages of multimedia teaching are enumerated, and the problems in courseware making, application and management are pointed out. Some methods to solve the problems are proposed. Related Articles | Metrics

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The product emotion and key technologies for emotional measurement Lin Li, Yang Mingqing, Zhang Chao, Liu Lingling 2013, 34(1): 122-127.  Abstract ( 144 )   PDF (316KB) ( 612 )   In order to realize a well-designed product that appeals to consumers, the product should not only meet the physical requirements of consumers, but also satisfy their affective (psychological) needs. Based on the investigation of related literature, the research status of product emotion and emotional measurement technologies are discussed. The method, name, properties, characteristics and deficiency of the emotion measurement technologies are summarized. Finally, the future development trend is outlined. Related Articles | Metrics

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Ship navigation training oriented large scale terrain modeling Xiao Jianbo, Hu Dabin, Zhao Kai 2013, 34(1): 128-132.  Abstract ( 97 )   PDF (852KB) ( 205 )   Real-time rendering of large scale terrain plays an important role in virtual reality, battlefield simulation and training areas and so on. To meet the requirements of scene simulation in ship navigation training, the modeling and rendering of large scale terrain are studied. Some usual DEM interpolation is studied at first, and then the DEM interpolation based on data fusion is used. According to the practice of navigation training, a terrain culling method based on visibility estimation is proposed. The method uses radiated ray and searches for if there are points whose height is larger than the occlude ones. If there is a point with a larger height in all direction, it means that this point is being occluded. We cull all the occluded points to reduce the terrain model. At last, a terrain modeling method based on Google earth and Terri Vista is introduced. The results show that this method can get a good performance in real-time with no hurt to the verisimilitude. Related Articles | Metrics

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Automatic programming of engineering drawing of shaft part based on feature recognition Zhang Wanli, Wang Jine 2013, 34(1): 133-138.  Abstract ( 61 )   PDF (255KB) ( 187 )   A method to realize automatic programming of shaft part is proposed based on type-encoding and feature-encoding of entities. The paper first presents a method of entity-breaking based on pitch point set, and introduces the method of minimum anti-clockwise angle for searching the outline. Secondly, the type and feature of the entities is encoded which constitute the outline. And then, the main feature is extracted and the assistant feature is reconstructed. At last, according to the reconstructed outline, NC code is generated automatically which can be recognized by CNC lathe. With a typical shaft part as an example, a program is developed under the AutoCAD 2002 with ObjectARX, and verifies the methods and principles proposed, which gives an effective result. Related Articles | Metrics

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A method for people counting based on optical flow and pedestrian size Tang Shichen, Chen Duansheng 2013, 34(1): 139-134.  Abstract ( 95 )   PDF (391KB) ( 242 )   In order to improve the accuracy of people counting in video surveillance, an approximate pedestrian size in the vertical view is proposed as a feature when the camera is mounted vertically. In this method, a virtual detection line is set up and the Lucas-Kanade optical flow algorithm is used to calculate the velocity vector of pixels on the line. The method constructs the approximate pedestrian size in the vertical view to estimate the number of people passing through the detection line. Experimental results show that this method can reduce interference caused by shadows and image preprocessing, and can accurately count the number of people passing through the entrance. Related Articles | Metrics