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25 February 2011, Volume 32 Issue 1 Previous Issue    Next Issue

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Integer Algorithm of Midpoint Generating Ellipse ZHANG Bo, ZHOU Li-yun, LI Xing-xia 2011, 32(1): 1-4.  Abstract ( 124 )   PDF (361KB) ( 297 )   Based on the research on circle and ellipse generating algorithm, integer algorithm of midpoint generating ellipse is presented by constructing recursion expressions, whose efficiency is also analysed. In initialization, the algorithm needs conduct multiplication twice and shift operation once, and every graphic point is calculated by integer addition, so the algorithm is fast and precise and can be realized by hardware. The correctness of the algorithm is tested by VB programming, and it is of theoretical and practical value. Related Articles | Metrics

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A Ladder-type Method Based Genetic Algorithm for Product Shape Design WANG Jun-feng 2011, 32(1): 5-9.  Abstract ( 117 )   PDF (522KB) ( 186 )   Based on the parameterized coding of product shape, the method that lets customers participate the process is used to evaluate parameters’ weights. According to the order of the parameters’ weights, the shape coding of product design is sorted. The data is processed by the ways that degrade the ladders, and the seeking optimal is searched through interactive genetic algorithm. Then the product shape detail is determined gradually. The solving process is thoroughly based on decoded product shapes, which provides designers the visualized interface. Related Articles | Metrics

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Three-dimensional Parametric Modeling of Human Body for Analysis of Seat Comfort HUANG Lu, YANG Yue, PENG Bo 2011, 32(1): 10-15.  Abstract ( 157 )   PDF (544KB) ( 376 )   Three-dimensional human body sitting model can be used in the design phase of seats to achieve accurate and efficient analysis of seat comfort. A two-dimensional sitting posture template of human body model is taken as reference to define the structure element of the three-dimensional human body sitting model, and a three-dimensional human body model is built by feature-based modeling approach. The three-dimensional human sitting model is driven in parametric way by parametric modeling method based prototype model. Through the geometric model matching between "people-chairs" model, the joint gesture angles of the sitting human body model are extracted automatically. By contrasting the scope of human sitting standard comfort angles, it can analyze and evaluate the seat comfort. Related Articles | Metrics

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Design and Development of CAE Process Automation System Based on HyperWorks CAO Wen-gang, FAN Chao 2011, 32(1): 16-21.  Abstract ( 131 )   PDF (633KB) ( 499 )   Aiming at sovling the problems of complexity and substantial experience needed in using HyperWorks to do CAE analysis for enterprise, the structure and development process of HyperWorks CAE process automation system is given based on HyperWorks Process Mananger and Process Studio. CAE process automation system is developed by using the Tcl/Tk programming technology. CAE analysis result of some product parts demonstrates the operability of CAE automation system. It provides a shortcut for designing and analyzing products and reduces the analysis and design cycle of the product eventually. It has a great guiding significance for enterprise development work. Related Articles | Metrics

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Global Modeling for Composite Elbow Surface DU Hong-yun, TANG Yue-hong, SONG Bo 2011, 32(1): 22-25.  Abstract ( 125 )   PDF (412KB) ( 156 )   For improving smooth transition of the elbow and keeping geometric modeling characteristics of the elbow, the equation of blending surfaces was established by the means of implicit geometric modeling. Adjustable function of controlling parameter increases freedom of blending surfaces modeling. Sudden changes of stresses at three conjunctions, which are the conjunction of anchor ring and small circular cylinder, the conjunction of small circular cylinder and blending surfaces, the conjunction of blending surfaces and big circular cylinder, are all very small by analyzing stresses of the elbow. This illustrates that bending effect of the elbow is good. It is feasible to use the blending surfaces for the elbow. Related Articles | Metrics

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A Method for Constructing Identical Slope Surface Based on Parametric Spline Interpolation LI Jun-cheng 2011, 32(1): 26-30.  Abstract ( 122 )   PDF (473KB) ( 281 )   The traditional method for constructing identical slope surface is under the premise that exact expression of lead curve is known. But in practical engineering, the exact expression of lead curve is hard to obtain, and only some measured data points of the lead curve are given. For solving that problem, a method of constructing the identical slope surface in engineering is presented in this paper. Firstly, cubic parametric spline interpolation curve is constructed according to the measured data points, which is regarded as the lead curve. Then, the parametric equation of identical slope gradient surface is constructed based on the forming principle of that surface. Lastly, an example is presented to show the method is feasible and effectual. Related Articles | Metrics

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Extensions of Hyperbolic Bézier Curves ZHANG Jin-xiu, TAN Jie-qing 2011, 32(1): 31-38.  Abstract ( 94 )   PDF (651KB) ( 188 )   Hyperbolic Bézier curve (briefly H-Bézier curve) with multiple shape parameters is presented in this paper. The curve not only possesses most of the properties of the Bézier curve, but also can be adjusted totally or locally by taking the different values of shape parameters, with increasing of the shape parameters the curve can well approximate the control polygon. Moreover, the curve can represent hyperbolas and catenary exactly. At last, the C1continuous joint of curve pieces is discussed and some examples are provided to illustrate the application in geometric modeling. Related Articles | Metrics

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A Human Recognition Scheme Based on Mean Gait Energy Image ZHANG Qian-jin, CHEN Xiang-tao, BU Wen-shao 2011, 32(1): 39-44.  Abstract ( 146 )   PDF (626KB) ( 171 )   An embedded hidden Markov model(e-HMM) human recognition scheme based on gait energy image(GEI) is proposed. First a preprocess technique is used to segment the moving silhouette from the walking figure. The algorithm obtains the gait quasi-periodicity through analyzing the width information of the lower limbs’ gait contour edge, and the mean GEI is calculated from gait periodic. It makes use of an optimized set of observation vectors obtained from the two dimensional discrete cosine transform(2D-DCT) coefficients of the mean GEI regions. The e-HMM is trained and used for the gait recognition. The proposed algorithm is evaluated on USF and CASIA Gait Database. The experimental result shows that the proposed approach is valid and has encouraging recognition performance. Related Articles | Metrics

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An Improved Super-resolution Reconstruction Algorithm of Video Sequence and Its Application ZHOU Fang, JIANG Jian-guo, WANG Pei-zhen 2011, 32(1): 45-51.  Abstract ( 129 )   PDF (800KB) ( 159 )   An improved reconstruction method to enhance the image resolution for multi-frame video sequence is proposed based on jointly making use of the techniques of Maximum A Posteriori Probability (MAP) and Project Onto Convex Sets (POCS). At first, a simplified spatial-domain estimator is employed by introducing the preconditioned conjugate gradient method to forecast the original high-resolution image. Then, under the wavelet-domain, two different convex sets and projection operators are designed from the aspects of inter-frame and intra-frame to extract the details hidden among the adjacent observed low-resolution frames. At last, taking advantage of the relationship between the neighborhood factors in the spatial estimator to put constraints on the potential solutions of the POCS, it can get uniqueness optimal solution quickly. The results of the simulation experiment and practical application of supervisory system demonstrate that the proposed method not only outperforms the other methods on the aspects of PSNR (Peak Signal-to-Noise Ratio) and visual quality of the reconstructed sequence, but also has the advantages of rapid convergence and great robust. Related Articles | Metrics

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Blind Image Watermarking in Contourlet Domain Based on Improved Modified Spread Spectrum Technique YANG Sheng-li, GAO Jun, SUN Rui 2011, 32(1): 52-58.  Abstract ( 84 )   PDF (701KB) ( 308 )   A blind image watermarking algorithm in contourlet domain based on improved modified spread spectrum (IMSS) technique is proposed. The original binary watermark is firstly scrambled by two-dimensional Arnold transform and mapped from unipolarity to bipolarity, and then embedded into the richest textured region of the subband, which has the maximum energy among the second biggest directional subbands of the host image decomposed by the contourlet transform. Meanwhile, the IMSS technique is adopted in the process of watermark embedding. The watermark embedded is retrieved by computing the correlation between the watermarked coefficients and the pseudo random sequences. The optimal threshold is calculated to determine the existence of the watermark in the correlation detector. Experimental results demonstrate that the proposed algorithm not only has good imperceptibility but also has higher robustness against common image processing and attacks than conventional SS (spread spectrum) watermarking; furthermore, it overcomes the major disadvantage of conventional SS watermarking which completely fails if the tested image is pure. Related Articles | Metrics

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Image Stitching Based on Empirical Mode Decomposition ZHANG Xiao-yu, DAI Fang, GAN Ming-hui, WANG Sai-fang 2011, 32(1): 59-66.  Abstract ( 105 )   PDF (1409KB) ( 155 )   The first two intrinsic mode functions of each image are obtained by using empirical mode decomposition algorithm to decompose images which need stitch. Through this method, the feature points are extracted and matched from the first two intrinsic mode function’s superimposition of each image. Based on these matched feature points pairs, parameters of the transformation matrix are calculated and then images are stitched. Experimental results have shown that this method effectively improves the accuracy rate of the feature points matched and has strong robustness. On image fusion, a novel weighed technique based on cosine relationship transform is proposed. With this technique, not only the seamless stitching images can be obtained, but also the phenomenon of ghosting in the overlapping stitching region can be eliminated. Related Articles | Metrics

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Image Segmentation Algorithm Research Based on Minimum Within-cluster Difference and Maximum Between-cluster Difference WU Hao, WANG Rong-gui, FANG Shuai, YANG Wan-ting 2011, 32(1): 67-75.  Abstract ( 120 )   PDF (600KB) ( 203 )   The present two-dimensional Otsu image segmentation algorithm ignores the cohesiveness of foreground and background pixels. A novel method of threshold recognition algorithm is proposed, which, by using two-dimensional histogram of the target image, counts the absolute difference within the cluster and the average total deviation between the cluster to reflect the scattered difference, and then constructs a new threshold recognition function. An improved genetic algorithm is adopted to optimize the new threshold recognition function so as to obtain the ideal threshold value automatically. Experimental results show that the two-dimensional threshold value obtained through the optimized threshold recognition function is of good segmentation efficiency, of good retaining of the object outline and of low work amount of calculation. Related Articles | Metrics

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Study on Building Virtual Three-coordinate Measuring Machine Based on Eonstuido Technology LOU Yan, LUO Feng, SHE Ai-yong, HU Lin 2011, 32(1): 76-82.  Abstract ( 115 )   PDF (636KB) ( 207 )   Eonstudio is a most perfect virtual reality language. By using Eonstudio technology, the virtual human-computer interaction machine is built to avoid the damage of expensive equipments and reduce cost, which can also be applied to the training system of expensive equipments. The key technologies are real model construction and dynamic simulation interaction. Firstly the technology of map unwrapping and rendering to textures are used to build more real virtual three-coordinate measuring machine. Then the Eonstudio technology is developed to realize the human-computer simulation interaction. Finally the model of windows sockets are selected to realize the information communication between the two computers. Thus the virtual three-coordinate measuring machine is built. A prototype system is implemented to testify its applicability and validity. Related Articles | Metrics

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Automated Labeling for Virtual Assembly and Its Application in CRH Train ZHOU Shao-ze, ZHAO Wen-zhong, ZHANG Jun, MA Si-qun 2011, 32(1): 83-88.  Abstract ( 91 )   PDF (857KB) ( 213 )   Automated labeling can significantly improve practicability of the virtual assembly and virtual prototyping technology of complex products. To resolve the problems of real-time label layout for virtual assembly of complex products, the fast interactive label layout algorithms are presented. Through predefining label position, setting up the rules of label overlap elimination and dynamic adjustment of labeling, fast point-feature labeling placement and left-right-feature labeling placement for moving 3D objects of models are realized. The experiments show that this approach significantly increases readability of complex product models in the virtual assembly system, enhances the overall effectiveness of the simulation and improves the design and training efficiency. Related Articles | Metrics

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Construction of Reducer Virtual Disassembly and Assembly Experiment System FENG Gui-zhen, CHI Jian-bin, WANG Da-ming, WANG Chen 2011, 32(1): 89-92.  Abstract ( 132 )   PDF (552KB) ( 308 )   In view of the lack of experiment equipment and place, analyzing the current condition and features of virtual labs. On the basis of studying the process, method and related technology of constructing 3D interactive virtual scene with Cult3D, taking the gear reducer as example, a gear reducer virtual disassembly and assembly experiment is constructed with Cult3D and other related software tools. The virtual experiment system is proved to be of good efficiency in practical application owing to its characters of three-dimension，dynamic, interaction, low-bandwidth transmission, and overcoming the discomfort of traditional experiment. Related Articles | Metrics

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Optimization of Triple-side Cooperation in the Complicated Customer Interface Design DUAN Nian, LAI Ya-lin, LI Min 2011, 32(1): 94-98.  Abstract ( 98 )   PDF (494KB) ( 191 )   With the high-speed development of high-performance CMOS chip and hardware condition, the traditional customer interface design becomes a very troublesome work. This paper analyzes the limitation of the traditional customer interface design method and the optimization of designing customer interface in the complicated game. Experimental results shows that the adoption of this method can greatly reduce the time consumption of complicated interface cooperation. Related Articles | Metrics

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The Design of Virtual Human’s Action Models in Virtual Maintenance CHANG Gao-xiang，XU Xiao-gang，ZHANG Lei 2011, 32(1): 99-103.  Abstract ( 99 )   PDF (546KB) ( 254 )   Based on the mission of virtual maintenance, the process of maintenance are separated into three courses, and three corresponding straticulate action modes are established, the sort and design of maintenance action are expatiated, and the maintenance action models are applied in virtual maintenance. The experimental results indicate that the action models of virtual human based on decomposing maintenance mission can improve greatly the reality of virtual maintenance. Related Articles | Metrics

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Study on the Texture Synthesis of Triangular Mesh Surfaces WANG Yuan-long, ZHANG Rong-guo, FENG Jun-hua, LIU Kun 2011, 32(1): 104-110.  Abstract ( 145 )   PDF (468KB) ( 257 )   Texture synthesis is an important technology in a realistic figure rendering. A texture synthesis method is presented which is based on surface triangular mesh vector field for surface model consisting of the triangular mesh. First, the texture vector direction of each triangle of surface is calculated by using the vector sum method, and the texture vector direction is used to synthesize surfaces texture. Second, the best match of the texture coordinates is found in the sample texture space by scanning line sequence. The algorithm uses a queue as the structure of depositing and withdrawing, and the results are stored in the queue to achieve real-time rendering. Some experimental results and theoretical analysis show that texture synthesis quality of algorithm is higher and running results are better. Related Articles | Metrics

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Resolving Pose and Occlusion Consistency Based on Multiple View Geometry for Augmented Reality Systems ZHANG Yan, HE Xiao-bo, GUAN Tao 2011, 32(1): 111-118.  Abstract ( 151 )   PDF (754KB) ( 336 )   This paper proposes a novel method to solve pose and occlusion consistency problems by using multiple view geometry for AR systems. The method can deal with pose and occlusion consistencies simultaneously in an uniform framework, which improves the performance of AR systems obviously. Experiments have been carried out to demonstrate the validity of the proposed approach. The results indicate that the method can solve pose and occlusion consistencies problems, by which the wrong impression of relative position caused by incorrect occlusion can be avoided effectively. Related Articles | Metrics

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The Visualization Research of Artificial Upper Limbs Inverse Kinematics Resolution LIU Xiao-yang, LIN Da-jun, ZHENG Peng-fei, WU Zhi-ting 2011, 32(1): 119-123.  Abstract ( 125 )   PDF (587KB) ( 259 )   A method based on algebraic and identity conditions for mechanism is presented to solve artificial upper limbs inverse kinematics problems. The method can avoid multi-times inverse matrics mutiplication in the course of deduction. The spatial positions of each joint angel are shown in CATIA by secondary development of CATIA with VB. It can determine the solutions directly and lay the foundation for movement research of artificial upper limbs. Related Articles | Metrics

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Research on Form Design of Product Image Based on Fuzzy Logic LI Yong-feng, ZHU Li-ping 2011, 32(1): 124-128.  Abstract ( 126 )   PDF (610KB) ( 174 )   In order to design the products that meet consumer emotional demand, the method of product image form design based on fuzzy logic is adopted. The first of all is to ascertain the kansei words and the design elements. Based on this, the relationship between them is built by using fuzzy logic. Through fuzzification, fuzzy rules’ construction, fuzzy reasoning and defuzzification, the fuzzy logic controller is designed, and the simulation model is established by using Matlab. Finally, the validity of the model is verified by testing. This study is carried out combining form design of folding bike, and the results show that this method is valid and feasible. Related Articles | Metrics

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Reform and Implementation on the Skill Training of Engineering Drawing ZHANG Shu-min, CHEN Shu-bin, CHEN Gang 2011, 32(1): 129-133.  Abstract ( 117 )   PDF (497KB) ( 200 )   Presently the vocational ability training and the operation skills are the emphasis of higher vocational education reform. Engineering Drawing is a basic course in Mechanical and Electrical Engineering. But now the course’s period has been reduced. How to take effective teaching is a big problem. The paper provides a solution. Firstly, after analyzing the demand for corresponding positions and inducing the representative work process, the paper establishes the curriculum goal, and then builds a training framework, which includes “one standard, two techniques and three skills”. Secondly, the training contents are also restructured. The main contents are single 3D projection and more complicated 3D projection. Eventually, this paper puts forward a skill training implementation plan. The plan takes Specific missions as carriers, some theme as the core of the teaching and cognitive apprenticeship learning as training mode. Related Articles | Metrics

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Application of Multiple Intelligence Theory in Engineering Graphics Teaching YI Zhen-zhen, YAN Hui-e 2011, 32(1): 134-137.  Abstract ( 131 )   PDF (412KB) ( 205 )   Multiple Intelligence theory, with its rich substance of education, provides a new perspective for quality education in college. The paper starts with the features of Multiple Intelligence theory and the current tendency of engineering graphics teaching, and then explores the application of Multiple Intelligence theory to engineering graphics teaching. The further discussion centers on how to improve teaching quality and enhance the training of students’ integrated quality from the perspective of outlook on education, participants in teaching, teaching methodology and evaluation system, etc. Related Articles | Metrics

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Learning Situation Design in Courseware of Engineering Graphics CHEN Cai-ping, TAN Jian-rong 2011, 32(1): 138-142.  Abstract ( 100 )   PDF (490KB) ( 325 )   The design of learning situation is an important part in the courseware development process. How to introduce the learning content into the specific scenario is the key to the courseware development. This article describes the real mapping situation, from shape to the drawing, visual image and simulation learning environment design approach. In the courseware development process, we aim at meeting the students' cognitive structure, authenticity, selectivity, attractiveness and holisticity, using Powerpoint as a platform, using AutoCAD, Solidworks, Flash and 3DSmax as the multimedia technology, analying the students' difficulties in their study, designing different learning situations in order to develop their image thinking and innovation ability. Related Articles | Metrics

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A Function Family Solving Method of And/Or/Not Function Tree TANG Yi-ming, LIU Xiao-ping 2011, 32(1): 143-147.  Abstract ( 117 )   PDF (512KB) ( 152 )   Combination solving is widely used for and/or/not function trees in conceptual design. However, there exist some serious problems such as enormous solving space and difficult conflict orientation in combination solving. A function family solving method is proposed. At first, the concepts of function families and generalized and/or trees are given. Furthermore, and/or/not function trees are equivalently converted to the generalized and/or trees based on classical propositional logic. At last, the function solving algorithm is realized by obtaining function families. The new method is proved to enhance designers’ work efficiency with an instance. Related Articles | Metrics

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Research on Virtual Enterprises Task Scheduling Based on Timed Place Petri Net HUANG Bin, GAO Cheng-hui, CHEN Liang 2011, 32(1): 148-153.  Abstract ( 120 )   PDF (462KB) ( 164 )   Considering the characteristics of virtual enterprises task scheduling, timed place Petri-net(TPPN) based approach is proposed to model the task scheduling. On the basis of formal definition and transition rules of the TPPN, product manufacturing types in virtual enterprises are classified, and the TPPN model of each kind of manufacturing is provided, then the methods of resolving critical path with place zero activity floats and solving reasonable scheduling scheme with reachability graph are analyzed. Finally, the simulation of a case indicates that the approach is feasible and effective. Related Articles | Metrics

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Consideration on the Drawing about Cone Roller Bearing YU Xiao-qin, WU Shu-hui, SUN Jin-feng, YANG Huai-yu 2011, 32(1): 154-157.  Abstract ( 134 )   PDF (375KB) ( 314 )   In the Standard of P.R.C《GB/T 4459.7-1998 Mechanical drawings— Representation of rolling bearings》, there is a convention in characteristic drawing of cone roller bearings. By contrasting the width of the drawing to the fact, the article points out two problems: to some cone Roller Bearings, the drawing can’t express the principle of a mechanical system in the assembly drawing; and is contradictory to the words in this standard. The paper provides some suggestions to solve the problem. Related Articles | Metrics

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Part Building Orientation Optimization Based on Pareto Optimal Solutions LIU Hou-cai, LIAO Yan-chun 2011, 32(1): 157-162.  Abstract ( 110 )   PDF (549KB) ( 173 )   The effect of part building orientation on the part’s surface quality, the needed supporting area and building time is analyzed in the processing of rapid prototyping, and their optimizing models are established. The multi-objective optimizing generic algorithm of NSGA-II based on Pareto optimal solutions are used to seek the optimum solutions. Compared with the results gained by the single-objective optimizing way, it is shown that not only the better solution is gained but also many Pareto optimal solutions can be gained in one optimizing computing by NSGA-II. Related Articles | Metrics

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Research on Model State Generation Based on Hole Defeature in Finite Element Analysis JIN Can, LIU Xiao-ping, WU Min 2011, 32(1): 163-167.  Abstract ( 104 )   PDF (425KB) ( 179 )   The finite element analysis toward complex geometrical model is always a time-consuming task. How to reduce the computation cost with required result precision turns out to be a research focus. The theory of Multi-State Model is introduced to solve this problem, whose key technique is to generate appropriate model state which has critical influence upon computation cost. Since holes in model will contribute largely to huge computation task, based on the technology of feature remove, appropriate simplification strategy toward holes in model is researched, and computation task and result precision of the generated model state are evaluated respectively. A preliminary summary on factors that have relation to result precision and computation task is given in this paper. Multi-Objective problems can be transferred to Single-Objective problems according to classical Multi-Objective resolution, so the most appropriate model state can be gained by using selection algorithm after the establishment of selection criterion. Related Articles | Metrics

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Research on the Optimization of Engineering Drawings’ Adjusting Technology in Parametric Variant Design HUANG Qi-liang, WANG Zong-yan, WU Shu-fang, QIN Hui-bin 2011, 32(1): 168-173.  Abstract ( 113 )   PDF (627KB) ( 251 )   Aiming at the existing deficiency of engineering drawings’ adjusting technology, such as the imperfectness of methods, the long consumption of time, the complexity of process, etc, an optimization for them is implemented. The benefits and shortcomings of commonly used view scale adjusting method are analyzed and its adjusting process is optimized. By studying the stretch law of model edges, presenting the concept of dimension angle and drawing the assembly layout sketch based on it, the adjustment of view position is simplified. Through putting forward the concept of annotation binding element, discussing the effect it has on the position of dimensions and annotations, and adopting the marking method based on it, the adjustment of dimensions and annotations is simplified. Related Articles | Metrics

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Function Graphic Data Model for Road Bridge Construction Problem Solving HUANG Ling, LI Yan-qiang, FU Li-yong 2011, 32(1): 174-179.  Abstract ( 109 )   PDF (425KB) ( 169 )   In view of the defects existing in present engineering data models for the road bridge construction problem solving, the function graphic data model is provided. Taking the function graphic modeling technology as the instruction, with the feature line and the feature line array as the basic data structure, this paper introduces the length-variable and unstructured engineering graphs, conducts the related graphic and professional computation, describes the collaborative relationship among feature line arrays, and the model supports dynamic computation process for function graphic objects. The result proves it a new way to create complicated engineering graphic objects with simple data structure and its engineering application value in engineering software development. Related Articles | Metrics