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30 June 2017, Volume 38 Issue 3 Previous Issue    Next Issue

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Realistic Simulation of Physical Animation Based on Lagrangian Particle Method SHAO Xuqiang, JING Xiaozhu, LIU Shugang 2017, 38(3): 297-302.  DOI: 10.11996/JG.j.2095-302X.2017030297 Abstract ( 367 )   PDF (7469KB) ( 109 )   Realistic simulation of different types of objects in real world is an important task of physical animation. However, it is still hard to realize simulating based on a unified numerical method. Based on smoothed particle hydrodynamics and continuum mechanics, we propose a unified particle-based method to simulate physical animation, and realistically simulate rigid objects, elastic objects and incompressible fluids. Moreover, by combining the adaptive sampling scheme and relative contribution computation of surface particles of objects, we present a stable fluid-solid coupling algorithm. The results demonstrate that our method is suitable for the unified modeling and simulation of different objects in virtual scenes. Related Articles | Metrics

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Tree Crown LOD Modeling Based on α-Shape ZHU Xiaoqiang1,2, ZHOU Hao1,2, SONG Lei1,2 2017, 38(3): 303-313.  DOI: 10.11996/JG.j.2095-302X.2017030303 Abstract ( 69 )   PDF (4719KB) ( 214 )   Based on 3D Delaunay theory, an optimal α is selected to construct the minimal connected α-shape from the input point cloud of a tree model. After the calculation and filtering of its distance field, a smooth distance surface is extracted, from which the bounding volumes of tree trunk and crown are segmented respectively based on the Laplacian skeleton-based segmentation approach. Finally, the point cloud within the crown volume is utilized to generate multi-resolution α-shapes, which can be used as levels of detail (LOD) models in non-photorealistic VR environment. Related Articles | Metrics

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Mesh Simplification Weighted by Voronoi Poles Feature Computed Saliency WEI Ning, XU Tingting, GAO Kaiyuan, DONG Fangmin 2017, 38(3): 314-319.  DOI: 10.11996/JG.j.2095-302X.2017030314 Abstract ( 90 )   PDF (1977KB) ( 282 )   In this paper, we represent a novel method for mesh simplification. Compared with conventional methods that are based only on local features, our method exerts visual saliency feature as the weight to sample points during simplification, hence has better performance on persevering visual features. Firstly, the method computes the local feature values by the relationship between Voronoi-poles and the sample points. Then the global visual saliency features are computed by overlaying the Difference of Gaussian of local feature values get under different scales. Finally, the computed global visual saliency features are used as the weight to the quadric error metrics, in order to hold the positions where have of higher global visual saliency during iteration of the mesh simplification. The simplified results show that our algorithm not only gets better visual feature preservation but also smaller qualified errors comparing to state of the art methods. Related Articles | Metrics

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Sorting Method of Point Cloud Based on Grid Association and Quadtree ZHANG Li, LI Chengwen 2017, 38(3): 320-325.  DOI: 10.11996/JG.j.2095-302X.2017030320 Abstract ( 86 )   PDF (1374KB) ( 255 )   An improved method is summarized based on quadtree and grid to sort the point cloud data in this paper. Using least squares method fitting projection plane, the 3D point cloud data become two-dimensional after projection. Envelope edges are calculated through convex hull. And the envelope regions are gridded. An improved quadtree indexing method is used to associat the data point with the grids. The completion of sort depends on these grids. Finally, using MATLAB to achieve example codes demonstrating the feasibility of the proposed method. Related Articles | Metrics

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The Algorithm of Suspension Structure in Stereolithography LI Zhanli, WANG Yafang, YUE Guohua, LI Hongan, ZHANG Yun 2017, 38(3): 326-331.  DOI: 10.11996/JG.j.2095-302X.2017030326 Abstract ( 81 )   PDF (943KB) ( 356 )   In order to solve the requirement of adding suspension structure for parts in Stereolithography, an algorithm of automatic generation of suspension structure is proposed. Firstly, identified and extracted various suspension region of the entity model. Then, the projection plane in the direction of the processing is discretized into a grid by using the discrete identification method based on the area. At last, according to the suspension structure stress load condition, uniform sampling is used to obtain the points and the corresponding suspension structure is designed. Finally in the Visual studio 2013 development platform combined with VTK to achieve it. The experimental results show that the algorithm is correct and feasible, and it has been successfully used in practical machining. Related Articles | Metrics

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Research on Implicit Intention Recognition and Classification Based on Eye Movement Pattern MA Lisha, LV Jian, PAN Weijie, SHAN Junjun, PING Zhengqiang 2017, 38(3): 332-340.  DOI: 10.11996/JG.j.2095-302X.2017030332 Abstract ( 138 )   PDF (1622KB) ( 483 )   In the psychology and cognitive science, intentional modeling and recognition are considered to be the new models for creating human-computer interaction. Explaining user’s implicit intention recognition has been a hotspot in interaction design research. In this study, an implicit intention recognition system based on eye movement pattern and pupil size change was proposed. A baseline model was established to measure pupil size change. Eye movement experiment was conducted with a juicer as an example. Finally, the implicit intention is divided into two types: unintentional intention and purposeful intention, by using the classifier to process the experimental data. The experimental results show that the discussion of this paper has some reference significance to the research of implicit intention recognition, and provides support for product or system research and development. Related Articles | Metrics

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Optimization Design and Simulation of Mini Elliptical Trainer HE Zhanliang 2017, 38(3): 341-345.  DOI: 10.11996/JG.j.2095-302X.2017030341 Abstract ( 123 )   PDF (849KB) ( 262 )   In this paper, the track of the human ankle during running is considered based on human factor engineering in order to optimize the structure of the elliptical trainer. By analyzing the influence of each component parameters on the track of the human ankle, the optimum parameters of each component were determined. The Solidworks 2016 is used for the simulation of the elliptical trainer. The results show that: the best elliptical orbit is obtained when the r1=110 mm, r2=412 mm, r3=140 mm. The theoretical calculation results of the displacement, velocity and acceleration of ankle point are in accordance with the simulation results which verify the rationality of the structure design. The maximum stress during working occurs on the crankshaft, the optimum diameter of crankshaft is 22 mm, and less than the yield strength of the material, so that the structure is safe and reliable. Related Articles | Metrics

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The Research on Reduction of Saturation in Redesign of Color Code CHEN Jinchang, WANG Chaoran 2017, 38(3): 346-351.  DOI: 10.11996/JG.j.2095-302X.2017030346 Abstract ( 91 )   PDF (2334KB) ( 214 )   Basing on the feature that the color code could be redesigned, it explores the method reducing the saturation of color code which is helpful to designers’ redesigning. Designers can transfer color code into visual patterns; while during the redesign process, the color code’s recognition mode and color limit become designer's restrictions. According to the pattern of recognizing of color code, it discusses the problems during redesigning; on the basis of spatial color mixing, it proposes the method of “alternate recognizing”, and tests the feasibility through two experiments. In accordance with the analysis of experiment results, the “alternate recognizing” does not lower the recognition of color code and reduces the saturation of color code at the same time; and then it is beneficial to redesign the color code for designers. Related Articles | Metrics

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Image Matching Algorithm Based on Fractional-Order Gradient Operator FU Wancheng1,2, DA Feipeng1,2, HUANG Yuan1,2 2017, 38(3): 352-360.  DOI: 10.11996/JG.j.2095-302X.2017030352 Abstract ( 79 )   PDF (10493KB) ( 80 )   In order to protect more image detail features, an image matching algorithm based on fractional-order gradient operator to construct nonlinear scale space was proposed. The fractional-order gradient operator was introduced in conductivity function of classic nonlinear diffusion equation. In this process, the recent numerical schemes called fast explicit diffusion (FED) was used to build the nonlinear scale space. And the sequence of the FED time step sizes was rearranged by Leja ordering. In addition, a new interest point operator from the Hessian matrix was exploited to detect the keypoints and local intensity order pattern (LIOP) descriptor was applied in feature description. The experimental results show that compared with the state-of-the-art algorithm, the proposed algorithm has better performance in many geometric and photometric transformations. Related Articles | Metrics

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Virtual Restoration Method of Houma Convenant Tablets Based on Suprathreshold Stochastic Resonance LIN Suzhen, ZHANG Shangmin, SHI Xiaobo 2017, 38(3): 361-366.  DOI: 10.11996/JG.j.2095-302X.2017030361 Abstract ( 54 )   PDF (10203KB) ( 63 )   On the issue that Shanxi Houma convenant tablets is serious degraded, this paper does researches on extraction the text and virtual restoration. Combining image processing algorithms and human-computer interaction, a method of Houma convenant tablets virtual restoration based on suprathreshold stochastic resonance was proposed. Firstly, transform the original RGB image to hue saturation value (HSV) color space, and restore the brightness image by suprathreshold stochastic resonance (SSR), then use modified bilateral filtering Canny operator to extract text contour information, and combine with human-computer interaction to text contour restoring, finally, adopt the method of color transfer to restore the text after filling into the original cinnabar color. Experimental results show that the fuzzy words with poor stroke connectivity and faded color of Houma convenant tablets can be repaired effectively by digital image processing. Related Articles | Metrics

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Adaptive Boundary Detection Method Based on Multi-Quadric Quasi-Interpolation GAO Qinjiao1, ZHANG Shenggang2, ZHANG Jihong3 2017, 38(3): 367-372.  DOI: 10.11996/JG.j.2095-302X.2017030367 Abstract ( 72 )   PDF (1063KB) ( 303 )   This paper proposes an adaptive method for simulating one kind of geometric active contours (GAC) applying multiquadric (MQ) quasi-interpolation. The geometric flow is presented in its parametric form. Then the numerical scheme is obtained: Firstly the spatial derivatives of each variable are approximated applying the MQ quasi-interpolation; secondly the knots are moved according to the moving knots equation to pull the knots to concentrate in regions with large variations. Thirdly the forward difference methods are applied to approximate the temporal derivative of each variable. The resulting scheme is simple, efficient and easy to implement. Also images with complex boundaries can be simulated more efficiently on the basis of the good properties of the adaptive MQ method. Several examples of applications are shown in the paper. Related Articles | Metrics

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An Improved SIFT Descriptor Based on Cosine Kernel Function DING Lixiang, HE Chuan, LI Shujie 2017, 38(3): 373-381.  DOI: 10.11996/JG.j.2095-302X.2017030373 Abstract ( 92 )   PDF (1356KB) ( 214 )   The SIFT descriptor has been widely used in the field of computer vision thanks to its various invariant attributes; however, its high dimensionality results in redundant data and makes it time-consuming for application. Therefore, a novel algorithm, considering the inner relationship between gradient vectors in SIFT descriptor, is presented in this paper, which utilizes the principal component analysis method based on cosine kernel function. First, a principal component matrix, which is used to compute the principal direction of the projection matrix, is generated by using cosine kernel function to extract SIFT descriptors from the sample images. Then, the projection matrix is applied to the dimensionality reduction of the SIFT descriptors from the new images. In the experiment, we evaluate the performance of descriptors by means of image matching. The results indicate that our method can efficiently reduce the dimensionality and also obtain more matches without sacrificing the matching accuracy and meanwhile improve time performance. Related Articles | Metrics

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The Applications of Potato External Quality Detection Using Machine Vision ZHAO Jun, TIAN Haitao 2017, 38(3): 382-387.  DOI: 10.11996/JG.j.2095-302X.2017030382 Abstract ( 181 )   PDF (366KB) ( 302 )   The detection of potato surface quality is of great significance to the potato industry. This paper summarizes the applications of potato surface quality detection by machine vision at home and abroad. It includes the detection methods of potato’s weight, geometrical shape, surface defects and the classification methods acoording to surface defects. It describes the new approaches and progresses on potato surface quality detection as well as shortcomings in exiting methods. At the end of the summary, it outlooks the development tendency and research directions in the future researches. Related Articles | Metrics

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Iimage Retrieval of Integrated Block Color Volume Histogram and LGWBPs LIU Fanghui, GUO Hui 2017, 38(3): 388-395.  DOI: 10.11996/JG.j.2095-302X.2017030388 Abstract ( 55 )   PDF (1737KB) ( 181 )   A novel image retrieval method based on integrated block color volume histogram and local Gabor wavelets binary patterns (LGWBPs) is proposed to solve the problem of multiple feature fusion to improve the image retrieval efficiency, The proposed method can effectively extract the color and texture features of the image, and provide users with accurate image retrieval results. Firstly, the 4×4 block image is divided into nine blocks and the color volume histogram features of each block are extracted. Then, LGWBPs histogram features are calculated by using the defined LGWBPs operator, and the extracted LGWBPs histogram features are extracted. Finally, the two features are integrated to measure the similarity. The experimental results show that the proposed method can improve the accuracy of retrieval, improve the ranking of retrieval results and has good rotation-invariance, anti-noise and robustness of invariant features. Related Articles | Metrics

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Content-Aware Image Resizing Based on Bayesian Model WANG Yanling1, LI Guanglun2, LIN Xiao3 2017, 38(3): 396-402.  DOI: 10.11996/JG.j.2095-302X.2017030396 Abstract ( 72 )   PDF (22186KB) ( 225 )   In order to solve the problems that salient objects easy to be deformed, small objects easy to be deleted and multi-salient objects easy to be fused as the image resize in different display devices, this paper presents a new content-aware image resizing algorithm based on Bayesian model. The algorithm firstly uses the convex hull and the background prior to obtain the prior probability and the likelihood estimation required by Bayesian model, and calculate the saliency map using the Bayesian model. Secondly, after the new gradient map is obtained by multiplying the gradient map and the saliency map, the new gradient map and the saliency map gets a composite energy map. Finally, we use the composite energy map to resize the map by seam carving. The experimental results show that the algorithm compared with the previous algorithm can overcome problems of salient objects deformation and small objects, and reduces the happening of the multi objects fusion significantly. Related Articles | Metrics

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Target Tracking with Background Suppression and Multiple Filtering WU Zhengping1, WU Diyun1, SUN Shuifa2 2017, 38(3): 403-409.  DOI: 10.11996/JG.j.2095-302X.2017030403 Abstract ( 94 )   PDF (1391KB) ( 271 )   In order to design a moving target tracking algorithm with respect to real-time and stable tracking process, an approach named background suppression multiple filtering (BSMF) was proposed, which researched the problem of computing target center position, dynamic matching temple update, and scale-variant. Firstly, the algorithm maps the RGB figure of target area to 11 dimension color vectors to extract target main color describe vectors, get a background suppression weighted matrix, and then it multiplies with the gray tracking area pix matrix, the target center position in tracking area was calculated by correlation filter method after background suppression. Finally, located target area was calculated by pyramid-filter to get scale change coefficient. Meanwhile, BSMF algorithm was used to decrease various interference factors mixing up in matching template by dynamic matching template strategy. And the algorithm could achieve 17 FPS when run at Raspberry Model 3 and tracking performance is better than other algorithms which have the same computational complexity. Related Articles | Metrics

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The Image Detection Method for Wheel-Rail Relative Lateral Displacement MA Zengqiang, SONG Zibin, WANG Yongsheng, LIU Zheng 2017, 38(3): 410-417.  DOI: 10.11996/JG.j.2095-302X.2017030410 Abstract ( 80 )   PDF (10196KB) ( 177 )   The current contact measurement based on sensor is widely used in dynamic performance parameters detection for monitoring locomotive status and exploring the theory of locomotive safety. But it has several defects, such as being difficult to dynamic measurement、large zero drift and poor anti-jamming capability. In order to overcome these defects of the current contact measurement, the image detection method for wheel-rail relative lateral displacement, is proposed in this paper for that the wheel-rail relative displacement is the most direct reaction for wheel-rail contact status of locomotive. In the method, laser that maintained a certain angle with the ground hit on the plane of the wheel, and the wheel-rail relative lateral displacement can be acquired by the wheel center and laser on the change in position of the image. Consequently , the wheel center and laser position can be obtaining precisely. The experiment results show that the image detection method for wheel-rail relative lateral displacement can acquire wheel-rail relative lateral displacement, and it has great important significance to further exploring and evaluating locomotive safety mechanics. Related Articles | Metrics

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Research on Coal Cine Conitoring Image Based on Twice Bilateral Filter CHEN Changhua1, LIU Yu2 2017, 38(3): 418-424.  DOI: 10.11996/JG.j.2095-302X.2017030418 Abstract ( 102 )   PDF (12831KB) ( 242 )   Coal mine intelligent video monitoring system in the coal mine are widely used. However, due to the harsh down hole conditions, video surveillance frequently encountered accompanied by a variety of random noise of fog image. In view of the serious degradation and poor visual effect of the monitoring image, a fast image defog method based on the twice bilateral filtering (FDA-DBA) is proposed. First getting the environment brightness by quadtree, and then using the bilateral filter towards minimum channel map to obtain coarse scattering map and do further optimization to get high precise transmittance map, secondly using the tolerance mechanism to correct the transmission to get high precise transmission map and resolve color distortion in the bright area after dehazing, finally restore the fog degraded image based on the atmospheric scattering model. Experiments show that the algorithm in this paper can accurately recover the scene color and clarity, and get a real clear no-fog image, and has higher accuracy and robustness, what’s more, the relationship between the time complexity of this algorithm and the number of image pixels is a linear correlation, which makes the algorithm in this paper is suitable for the environment of coalmine intelligent video surveillance. Related Articles | Metrics

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Research on Modeling and Cutting Method of Virtual Gear Shaping for Non-Circular Gear YANG Yanfang, SUN Han 2017, 38(3): 425-430.  DOI: 10.11996/JG.j.2095-302X.2017030425 Abstract ( 96 )   PDF (621KB) ( 217 )   Because the pitch is the non-circular curve, the machining process of non-circular gear is complex, and the simulation is difficult. In this paper, for the manufacturing of non-circular gear, simulation of virtual gear shaping process from blank to finished product is realized, namely in accordance with the prior preparation of the G code (NC program), to drive virtual slotting machine in order to remove a virtual blank material. Through discretizing the blank model, in the cutting process, the cutting material node is removed from the scene to realize the machining simulation; through the tree scene graph structure, the virtual machining environment is built effectively; with the coordinated operation of the complex motion of NC gear shaper processing process, the simulation of machining process based on G code is realized. Using Visual Studio 2008 as a development platform, combined with open scene graph (OSG) graphics library, the forming process of the work piece is well reproduced, providing useful reference and improvement for product processing. Related Articles | Metrics

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Research of IFC-Based Automatic Quantity Take-off Method for Typical Beam-Column Model KUANG Siyu, ZHANG Jiachun, DENG Xueyuan 2017, 38(3): 431-438.  DOI: 10.11996/JG.j.2095-302X.2017030431 Abstract ( 98 )   PDF (946KB) ( 289 )   As a new concept and technology, Building Information Modeling is raising a new revolution in AEC/FM (architecture, engineering, construction and facility management) industry. However, the reliability and the flexibility of quantity calculation using BIM technology are difficult to coexist due to the complexity of data processing, the current BIM application fails to optimize the calculation process and improve the efficiency. Based on the IFC standard, this paper conducts a research about automatic calculation method of quantity. By analyzing the IFC-based expression of a typical beam-column joint and formulating the geometric equations of the related components, the overlap volume of beam-column which will meet the requirements of GB50500-2013 can be calculated automatically. This research proves that the IFC-based calculation method is feasible and able to improve the efficiency and precision of quantity take-off, which also demonstrates that the quantity take-off method can be irrelevant with BIM software and modeling paths. Related Articles | Metrics

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Research and Application of Construction Management Platform for Long- Span Bridge on BIM-Based Technology MA Shaoxiong1,3, LI Changning2, XU Hong2, WANG Chuang3, CHEN Cunli1, ZHAO Qin1 2017, 38(3): 439-446.  DOI: 10.11996/JG.j.2095-302X.2017030439 Abstract ( 239 )   PDF (4821KB) ( 493 )   Considering the features of design and construction of long span steel pipe concrete arch bridge, a CATIA bridge model adding plug-in and a construction management platform was developed using CATIA to build a 3D bridge model. This model was applied for the whole process of planning, design, and construction of the Yelanghe river double line bridge project——a long span steel pipe concrete arch bridge. Research shows building information modeling (BIM) technology can be used for guiding the site planning and designing the transportation line during the planning phase of the project, comparing the design scheme and optimizing the selection in the phase of design, as well as realizing the statistics of works, preparation of prefabricated components, hoisting of stiff skeleton, 4D simulation of construction and 3D technical disclosure. Adopting the BIM technology significantly improved the information construction management level of the bridge and efficiency of construction. It provides a new management approach of bridge design and construction. Related Articles | Metrics

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Extract Quantities of the Revit Model Based on China’s List Valuation Specification WANG Ru, FANG Chao, WANG Liushu 2017, 38(3): 447-452.  DOI: 10.11996/JG.j.2095-302X.2017030447 Abstract ( 401 )   PDF (957KB) ( 894 )   Quantities of extraction is an important part of the construction project based on BIM, The existing engineering calculation software(such as Glodon and Luban)can import the Revit model into its platform to calculate quantities, but part of the model data may be lost and there are strict requirements for transformation of the model and the name of the component, poor applicability. Revit as one of the currently most widely used BIM software, engineering extraction currently has a very high accuracy but the volume of the deduction rules and schedule feature does not meet our 《GB50500-2013_construction engineering bill pricing norms》requirements. In order to realize the localization of extraction of quantities based on the Revit platform, this paper used the Revit platform and Revit API, established a budget BIM model, the use of the secondary development of model components reset volume deduction rules and accordance coding member with the relevant parties to achieve a rapid and exact the extraction of the bill of quantities, proved the feasibility of the localization of extraction of quantities based on the Revit platform, improved the work efficiency and precision of the calculation of quantities, reduced material waste, reduced management costs and budget risks. Related Articles | Metrics

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Multiple Practice Teaching Reform of Product Mapping Course WANG Shuxia, ZHANG Qian, CAI Xupeng 2017, 38(3): 453-457.  DOI: 10.11996/JG.j.2095-302X.2017030453 Abstract ( 92 )   PDF (1048KB) ( 295 )   In this paper, a new method of multiple practice teaching reform for product mapping course is presented. It includes four aspects as follow. First, introduce 3D CAD technology to built modelling and detail drawing to replace ruler gauge drawing and to keep product disassembly, surveying in product mapping and freehand sketch drawing of parts and assembly. Then students’s innovation consciousness is improved by reducing redundant rules, increasing autonomous choice and stimulating students’ interest. Next, it is to improve students ‘consciousness of team cooperation and students’ oral communication and writing skills of the technical document. Last one is an evaluation mechanism which all students have right for participation. At the same time, secondary development for 3D CAD software is finished for preventing electronic homework plagiarism. A teaching practise for 7 years has proved that the multiple practise teaching reform can stimulate students’ interests and creativity which laid a foundation for later courses. Related Articles | Metrics

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Task Graph Partitioning Method Based on Manhattan Distance MA Xiao1, LI Yue2 2017, 38(3): 458-462.  DOI: 10.11996/JG.j.2095-302X.2017030458 Abstract ( 69 )   PDF (544KB) ( 202 )   Multi-core processor is often used to improve the calculation speed of the embedded system with high real-time requirement, therefore, it needs to disintegrate the functional task of the embedded electronic system with high complexity, mapping it into different sizes of processors to reliably perform the function of complex systems. Combining with the relevant graph theoretical basis, a task graph partitioning method is proposed with the Manhattan distance as the partitioning criteria. Take the binary multiplier as an example, dividing its task graph, and comparing the method with the re-partitioning method. Results analysis show that the number of nodes in task subgraphs is reduced by the partition, and the communication time between the task subgraphs is short relatively, this verifies the effectiveness of the partitioning method, which is conducive to the implementation of complex embedded electronic systems. Related Articles | Metrics