Table of Content

28 October 2008, Volume 42 Issue 10 Previous Issue    Next Issue

Development of IT Industry in China in the New Age

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Development of IT Industry in China in the New Age JIANG Ze-min 2008, 42 (10):  1589-1607.  Abstract ( 16792 )   Save The article explains the role and future trend of IT industry, and states that information technology represented by the internet and computers has brought about the third industrial revolution in history. An important impetus for economic growth in modern times, the IT industry has greatly promoted sustainable development and is profoundly changing mankind’s way of life and production. In discussing the development trend of world IT industry, the article suggests that with potential new breakthroughs in IT technology, the trend of agglomeration and integration of industries has become increasingly obvious, competition of intellectual properties and strandards is intensifying and ubiquitous networks is taking shape. It points out that China should bring into better play the role of IT industry as an “amplifier” in economic growth, a “transformer” in development mode and a “propeller” in industrial upgrading. It is important to follow a policy that emphasizes indepandent innovation, marketdriven approach, open and compatible technologies, integrated and comprehensive application, and serving both military and civil purposes, so that a quantum leap of IT industry will be achieved. China should advance industrialization with IT technologles and promote the IT industry in the course of industrialization in an effort to build an IT industry with Chinese characteristics. Greater efforts should be made to develop such core sectors as microelectronics, computer, software, key components and materials, as well as sectors with international competitiveness, including broadband mobile communication, nextgeneration network and information services. Continued improvement should be made in the policies guiding the development of IT industry with a view to making China a country with a strong IT industry by 2020. Related Articles | Metrics

Automation Technique, Computer Technology

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Universal Shop Scheduling Method for Manufacturing System with Evolution Algorithm HU Yan-hai1, 2, YAN Jun-qi1, MA Deng-zhe1 ,YE Fei-fan2 2008, 42 (10):  1608-1612.  Abstract ( 6770 )   Save The concept of universal shop scheduling problem (USP) was proposed based on the analysis of a real production system. A hybrid ant colony optimization (HACO) was developed to be applied to the USP. The results were compared with those of genetic algorithm. The numerical experiments make use of several benchmark instances whose scale is up to 75×20. Minimizing makespan is taken as the objective function. Both termination conditions of computation generation and solution convergence are tested for the computation. From the numerical experiments, it can be seen that when the computation generation is kept the same, HACO will make the solutions more convergent, and when the convergency is kept the same, HACO will consume less time. Related Articles | Metrics

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Saliency Detection Based on Phase Spectrum of Color Information LI Wu-yue1, LI Zhi-qiang1, FANG Tao1, HUO Hong1, GE Wei-li2 2008, 42 (10):  1613-1617.  Abstract ( 6757 )   Save It is still a challenge to build a computing model of saliency detection by simulating the complex human vision system. Combining the characteristics of human visual system and previous studies in saliency, a saliency detection model based on phase spectrum of color information was proposed. A saliency map, in which the regions of important targets are pop out, was generated by using the proposed model. The experimental results indicate that the saliency regions in complex scene detected by our method are consistent with the attention regions of human vision in bottomup stage. Related Articles | Metrics

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Research and Application of Sparse Algorithm of Boundary Element Matrix CUI Shu-biao, ZHANG Yun, ZHOU Hua-min, LI De-qun 2008, 42 (10):  1618-1621.  Abstract ( 5767 )   Save A method was brought forward to make the matrix become sparser because the memory space of the boundary element matrix is in direct proportion to the square of mesh number. An appropriate rule of sparsity is defined according to the characteristic of boundary element matrix at first. The matrix coefficients which are less than certain limit value are united into the adjacent elements. Afterward the matrix coefficient was evaluated as zero. And the matrix coefficient of partial adjacent elements can be incorporated into certain element by using this method. Then the boundary element matrix becomes a sparse one. By using this method, the memory space is reduced observably while guaranteeing the numerical simulation accuracy through numerical simulation. Related Articles | Metrics

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Preventive Maintenance Modeling of Cluster Tools for Fabrication Wafers Based on Markov Chain ZHOU Bing-hai, HE Ping, PAN Er-shun, XI Li-feng 2008, 42 (10):  1622-1626.  Abstract ( 5829 )   Save To improve the running reliability of cluster tools for fabrication wafers, and to reduce maintenance cost efficiently, a Markov chainbased modeling method for preventive maintenance was proposed. According to the characteristics of the cluster tools, five states are defined, such as the running state, preventive maintenance (PM) state, PM unrestore state, preventive repair (PR) state and PR unrestore state. A state transition model was built with the five states. On the basis of the proposed model, an expected preventive maintenance cost model was presented. Finally, the built model was tested with simulative experiment data. The results indicate that the Markov chainbased preventive maintenance model is valid for analyzing the expected maintenance cost rate per unit time according to different combinations of modeling parameters. Related Articles | Metrics

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3D Modeling and Motion Estimation of Elastic Articulated Objects from Image Points PAN Hai-lang1, SHI Lei2, DAI Yue-wei1 2008, 42 (10):  1627-1630.  Abstract ( 6099 )   Save This paper presented a new method of elastic articulated objects (human bodies) modeling based on a new revolving conic surface. The model includes 3D object skeleton and deformable surfaces which can represent the deformation of human body surfaces. The deformation of human body surfaces can be represented by adjusting only one deformation parameter for each limb. Then, the 3D deformation and motion parameters are determined by corresponding 2D image points with volume invariable constraint from a sequences of stereo images. The algorithm presented in this paper includes motion parameter estimation of the skeleton and parameter determination of deformable surface. Related Articles | Metrics

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A 3D Human Body Modeling Method Based on Neural Network DENG Wei-yan，LU Guo-dong，GENG Yu-lei，WANG Jin 2008, 42 (10):  1631-1634.  Abstract ( 6587 )   Save A method of 3D human body modeling was presented. The model of fourlayer feed forward BP(backpropagation) neural network was given. By making use of scanned body data, cutting planes were allocated to get the feature points of section contours of scanned body, and the training samples of the neck, bust, waist and hip were obtained. The weight and the feature curve modeling of the neck, bust, waist and hip can be got respectively after training. Based on section loops which generate from neural network, a 3D manikin was regenerated. Finally, the error analysis was done and the results show that the method can approach the real human body feature curve. It is an effective modeling way for the human body. Related Articles | Metrics

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Executable Specification of P Systems with Active Membranes and Its Implementation ZHANG Minaa,QI Zheng-weib,DONG Xiao-jua 2008, 42 (10):  1635-1639.  Abstract ( 5496 )   Save Based on rewriting logic, an executable specification method was proposed to specify the P systems with active membranes (PSAM) in Maude language. The purpose is to check the correctness of the model automatically and study the properties of PSAM with the help of computer. Six formal specifications were defined in Maude respectively for the six basic rules in PSAM, so that any given PSAM model can be specified formally. An example was presented to demonstrate how to specify the PSAM model, which is used to solve SAT Problem. The feasibility and correctness of the specification method are concluded practically, with the analysis of the result that is reduced by running the specification in Maude. Related Articles | Metrics

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A Parallel Collisions Detection Algorithm for Interactive Assembling Operation in Virtual Environment WU Dian-liang1,2, ZHU Hong-min1,2, FAN Xiu-min1,2 2008, 42 (10):  1640-1645.  Abstract ( 6196 )   Save Collision detection is a key technology in interactive virtual assembling operation. A new rapid collision detection algorithm for interactive operation in virtual reality (VR) environment was presented. It is an improved method of the conventional BV hierarchies method. According to the algorithm, a new method is used to compute BV hierarchies using regions partitioning on a polygonal model and a rapid overlapping check between facets and a BV. According to user’s operation collision detection pairs are determined; a parallel method based on PCs and Local Area Net (LAN) is developed to detect the collisions among many virtual objects. A method for dynamically modification hierarchies is developed for detecting overlapping between two BV hierarchies models. The performance of the algorithm is verified by means of an automobile underchassis assembling. The result shows that the method is applicable for all general polygonal models and can detecting overlapping during realtime simulation. Related Articles | Metrics

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Covert Storage Channel Identification Based on Labeled Finite Automaton YAO Li-hong1,2, ZI Xiao-chao1,2, PAN Li1, LI Jian-hua1 2008, 42 (10):  1646-1649.  Abstract ( 5512 )   Save The characteristic of an information system was analyzed while covert storage channels exist. Then a covert storage channel identification method was put forward. It models the system as a labelled finite automaton and identifies the potential covert storage channels automatically. Then the existence scenarios and the information transferring processes of these channels were described. Furthermore, the calculation of the channel bandwidth was discussed. Related Articles | Metrics

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An Adaptive Sampling Algorithm Based on Vector Field for Medical Volume Rendering TANG Wei, YAO Li-xiu, YANG Jie, QIN Hong-xing 2008, 42 (10):  1650-1654.  Abstract ( 6241 )   Save Aiming at the characteristic of medical volume rendering, this article studied the variety of vector field of data, analyzed the relationship between the grads vector field of the medical volume data set and the sampling frequency, then proposed an adaptive sampling algorithm, in which the volume area that is more to contribute to the final image would be sampled with highfrequency, and in a relative manner, the volume area that is less to contribute to the final image would be sampled with lowfrequency. In this way, the sampling step is adjusted adaptively, and the performance of volume reconstruction is improved. The experiments show that the performance of the volume reconstruction is improved by about 30%~60%, while the quality of image is ensured. Related Articles | Metrics

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Ant Algorithm for Lot Sequencing in Wafer Fabrication System YAO Shi-qing, JIANG Zhi-bin, GUO Cheng-tao, HU Hong-tao 2008, 42 (10):  1655-1659.  Abstract ( 6488 )   Save Lot sequencing optimization based on ant algorithm, which solves choosing lots from buffers to be processed in semiconductor wafer fabrication system (SWFS), was proposed. Furthermore, time complexity of this algorithm was analyzed and the improved form was given. According to the characteristics of reentrant in SWFS, the algorithm was designed through constructing the model of ant algorithm based on bottlenecks, and eventually Lot priority sequencing was obtained by iterative simulation. It can be seen from the simulation result that the new algorithm is superior to common dispatching rules in shortterm scheduling. Related Articles | Metrics

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Robust Deformable Medical Image Registration Using Optical Flow and Multilevel Free Form Deformation WANG Min-you, HU Hai-bo, QIN Bin-jie 2008, 42 (10):  1660-1664.  Abstract ( 6245 )   Save In order to track the brain tissue shift due to tumor resection during image guided surgery, this paper presented a framework for robust deformable registration based on the theory of optical flow, within which outlier detection is used to set up locallyrefined control points in multilevel free form deformation (FFD) model. Robust Mestimator was also introduced to weaken the effect of outliers in global optimization for getting improved registration result. This proposed method has successfully been applied to a number of registration tasks to demonstrate its applicability and robustness to outliers. Related Articles | Metrics

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Threshold Constraint Based DepthFirstSearch for BranchBound Algorithm Solving Asymmetric Traveling Salesman Problems ZHU Yi, YANG Gen-ke, PAN Chang-chun 2008, 42 (10):  1665-1668.  Abstract ( 6116 )   Save An integration approach based on heuristic strategies and branchbound algorithm was proposed for solving asymmetric traveling salesman problem. In this method, associated with each node of the branchdecision tree, a parametric solution of the relaxed assignment problem and a feasible solution obtained by patching algorithm are used to tighten the lower and upper bound. A hueristic strategy that conbines the threshold constraint based depthfirstsearch and weighted random breadthsearch is adopted to seek the optimal solution. Therefore, a feasible solution that is very close to the optimal solution can be found in comparatively short time. The computational results on data in the TSPLIB and a hot strip scheduling simulation show the efficiency of the proposed algorithm. Related Articles | Metrics

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Study on Integrated Management of Marine Remote Sensing Data TENG Long-mei1,2，LIU Ren-yi2，LIU Nan2 2008, 42 (10):  1674-1677.  Abstract ( 6071 )   Save This paper put forward an integrated management method of marine remote sensing data by integrating the technologies of WebGIS, spatial database and network communication. A realtime publication of marine remote sensing data was designed and realized which integrates the function of data browsing, data querying, data downloading, automatic batch uploading remote sensing data to database, automatic longdistance data distribution and so on. The network communication technology and the efficient and safe data transmission that is combination of the encryption and verification technology were discussed. The mechanism of doubleeffect database connection pool was also analyzed. The strategy was proposed that marine remote sensing data is visualized by integrating the technology of creating data files dynamically with the technology of visualization cache. Finally, the application results show the system can manage marine remote sensing data efficiently. Related Articles | Metrics

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Research of Covert Channels Based on Web Counters HU Wen-tao, XUE Zhi, CHEN Nan 2008, 42 (10):  1678-1681.  Abstract ( 5738 )   Save To avoid the limits of previous network storage covert channels which transmit covert information generally through packet head manipulation, a new idea was presented by using the plentiful, public Web counters for storage to construct a covert channel. Therefore, the encoder and the decoder do not need to establish a direct network connection, thus avoid the surveillances of many firewalls and intrusion detection system (IDS). A general noisy discrete memoryless channel (DMC) was modeled and the iteration algorithm of the DMC’s capacity was realized by C program language to compute the channel capacity. Several methods such as using multiple counters to increase rate were presented. One technique using pseudorandom sequence to scramble the sending information was used to enhance the covertness and the antinoise capability of the channel. The relationships between parameters and channel’s performance were analyzed through experiment. The result shows that the covert channel is feasible. Related Articles | Metrics

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RealTime Traffic State Estimation Based on Evidential Fusion KONG Qing-jie, CHEN Yi-kai, LIU Yun-cai 2008, 42 (10):  1682-1686.  Abstract ( 5675 )   Save In order to estimate traffic states more accurately by fusing multisensors in intelligent traffic surveillance system, this paper presented a federated evidential fusion method, in which the evidence theory and the federated filter are integrated. This method is successfully applied to a real urban traffic network for realtime traffic state estimation. Also it was testified that this approach can not only overcome the drawback that the evidence theory can not deal with conflict exactly, but also enhance the realtime performance and robustness of the evidential fusion system, because the structure of the federated filter makes it possible to combine the temporal information and the reliability of sensors into the fusion system. Related Articles | Metrics

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Study on the Choice of Disciplinal Function During Point Cloud Smoothing Based on Anisotropic Heat Diffusion ZHANG Xue-chang1, JIA Zhi-xin1, CHEN Xiao-bo2, XI Jun-tong2，YANG Guang-quan2 2008, 42 (10):  1687-1691.  Abstract ( 5900 )   Save The smoothing method based on the heat diffusion has a good effect to the point cloud with noise points, but how to choose a proper disciplinal function to smooth the point cloud is no answer. This paper proposed a method to decide the disciplinal function based on the fuzzy mathematics’s relevant function concept. The six special functions, such as drop semirectangle function, drop semiГ function, drop seminormal function, drop semiCauchy function, drop semitrapezia function and drop semimountain function, were analyzed. The answer was gotten that the variant has a nonlinear relationship with the result of disciplinal function. Some cases were used to validate the characteristics of disciplinal function. There is a new way to handle the point cloud during the preprocessing of reverse engineering or complex surface inspection. Related Articles | Metrics

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Measurement Method and Compensation Control for Unbalanced Moment of Inertial Platform YU Shuang, FU Zhuang, ZHAO Hui, ZHAO Yan-zheng 2008, 42 (10):  1692-1696.  Abstract ( 5848 )   Save A measurement and compensation method was proposed in order to eliminate the coupling effect on tracking accuracy and stabilizing capability due to unbalanced moment of inertial platform. The condition for static balancing of twoaxis gimbaled inertial platform was analyzed. Weight sensors were used to measure the static unbalance torque of inner and outer gimbal, then the calculation formulas of dynamic unbalanced moment during missile flight were derived. The simulation results of the built control model for inner gimbal in MATLAB/Adams show the effectiveness of the proposed compensation method for unbalanced moment. Related Articles | Metrics

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Robot Workcell Layout Optimization Based on Genetic Algorithm XIANG Bin-bin1，CHEN Wei-dong1，QI Li-wei2，ZHANG Dan-dan2 2008, 42 (10):  1697-1701.  Abstract ( 6211 )   Save This paper proposed a robot workcell layout optimization method based on genetic algorithm. This method applies engineer’s experience and knowledge in robotic manufacturing system to the description of geometric and kinematic restrictions, thus reduces search space, improves the computational efficiency and makes the layout meet the industrial requirements better. The method has been embedded in commercial robot programming and simulating software, and used successfully in layout design. A diecast application case validates the effectiveness of the method. Related Articles | Metrics

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Steadystate Objective Calculation for Constrained Predictive Control Systems Based on Goal Programming ZHENG Yi, WANG Bai-ping, LI Shao-yuan 2008, 42 (10):  1702-1706.  Abstract ( 6059 )   Save In the procedure of steadystate objective calculation, the soft constraints adjustment and objective relaxation were required for getting satisfying results when the optimization problem is infeasible. The goal priority factor was introduced to describe the priority of the constraints and objectives; thereby the soft constraints adjustment and objectives coordination were solved systemically in realtime steadystate objective calculation. Simulation was processed with the example of the shell heavy oil fractionators benchmark problem, and the result shows the validity of the proposed algorithm. Related Articles | Metrics

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Autonomous Localization Technique of Submarine Inpipe Robot Based on Multisensor Data Fusion WANG Zhong-wei, CAO Qi-xin, LUAN Nan, ZHANG Lei 2008, 42 (10):  1707-1711.  Abstract ( 5438 )   Save Based on lots of investigation and analysis for internal and overseas inpipe robot localization technology, a kind of localization method was brought forward, which firstly achieves rough localization using eddy current sensor to detect girth welds in pipelines, then carries out precise localization between adjacent girth welds by odometers. A production rule was presented to achieve faulttolerance processing for undetected girth welds, which are induced by inpipe robot’s unstable crawl speed, using distance information. Multiodometer was applied to get more reliable distance information and the consensus data fusion algorithm was adopted to process the redundant data, so inpipe robot’s localization precision is improved as well. The tests on experimental pipeline system and applications on project site show that the new inpipeline localization method for inpipe robot is effectual. Related Articles | Metrics

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Robust Reliable Control of Uncertain Time Varying StateDelay System: A Linear Matrix Inequality Method WU Jun-sheng, WENG Zheng-xin, TIAN Zuo-hua, SHI Song-jiao 2008, 42 (10):  1712-1716.  Abstract ( 5696 )   Save The robust reliable control design problem for uncertain systems with timevarying state delay as well as actuator failures in the input channels was discussed. A sufficient condition was established such that the closedloop system quadratic stability is satisfied for both the normal system and the system with possible actuator failures. The condition is a delaydependent one. A reliable state feedback controller was synthesized within the framework of linear matrix inequalities. The simulation results demonstrate the efficacy and validity of the approach. Related Articles | Metrics

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A 3D Reconstruction， Measurement and Collision System for Unmanned Pneumatic Caisson LI Bao-shun1, CAO Qi-xin1, ZHANG Lei1, JAY Lee2 2008, 42 (10):  1717-1720.  Abstract ( 5501 )   Save A 3D surface modeling, measuring and excavator collision detection system was presented. By using several 2D laser scanning sensors, the system can scan the whole surface in the pneumatic caisson. After registration and segmentation of point cloud, a real 3D scene of the working chamber of the pneumatic caisson can be modeled. With multisensor fusion, the collision detection of excavators and measurement of the pose of the pneumatic caisson can be done. The experiments show that the system has good performance and good stability and can be put into practical use. Related Articles | Metrics

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Robotic yoyo Motion Control with Visual Feedback JIN Hui-liang, YUAN De-hu, YE Qian, XIE Wen-hua 2008, 42 (10):  1721-1725.  Abstract ( 5509 )   Save The switching control strategy proposed here stabilizes the yoyo by determining when to start its activation. The discrete return map associated with the original continuous system was analyzed and shown to possess a single physically relevant fixed point. Stability is guaranteed as long as the control parameter, which determines the magnitude of the acceleration, is above a certain level. The stabilizing power of the proposed control algorithm is successfully demonstrated on a realtime robotic yoyo playing system. Theoretical predictions regarding the fixed point of the return map are confirmed experimentally. Related Articles | Metrics

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Modeling of a Small Scale Unmanned Helicopter DU Jian-fu1, Lu Tian-sheng1, Konstantin Kondak2, ZHANG Ya-ou1 2008, 42 (10):  1726-1730.  Abstract ( 5848 )   Save Based on the analysis of the difference between small scale unmanned helicopters and normal scale helicopters, the small scale helicopter was modeled as two rigid bodies: fuselage and main tail rotor. The dynamical model was deduced by Kane method, and another model considering the helicopter as one rigid body was also deduced for comparison. It shows that the kinematics and translational dynamics are the same, but they have different rotational dynamics. The response of the dynamics modeled as two rigid body is cosine while the response of the dynamics modeled as one rigid body is linear. The real flight experiments verify the validity of the model. Related Articles | Metrics

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Precision Control Scheme and Experimental Analysis of Hydraulic Servo System with Large Friction Torque MIAO Zhong-hua，LIU Cheng-liang，WANG Xu-yong，LI Yan-ming 2008, 42 (10):  1731-1735.  Abstract ( 5773 )   Save In order to obtain a high precision control performance for nonlinear hydraulic servo system in the presence of large frictional torque, a novel control scheme based on the slidingmode variable structure controller combined with friction state observer was presented. The slidingmodel variable structure control law and the slidingmodel friction state observer were detailed. The LuGre dynamic friction model and the sliding mode friction observer were adopted for friction compensation. The experimental results show that high precision control can be accomplished in the presence of large friction torque and very low velocities. Related Articles | Metrics

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A Nonlinear Inverse Perspective Transform Based Method for Camera Distortion Calibration LI Hao, YANG Ming 2008, 42 (10):  1736-1739.  Abstract ( 6659 )   Save Camera distortion calibration plays an indispensable role in the research of robot vision. A nonlinear inverse perspective transform based method was proposed. In the light of linear perspective model and distortion model, a nonlinear inverse perspective model as well as the relation between inverse perspective transform coefficients and distortion coefficients was derived. A function with distortion coefficients as the optimum was put forward and optimized. Because only few distortion coefficients are optimized, the optimization dimension and complexity are largely reduced. During optimization, the search direction is determined by improved Newton method and a try and error linear search method is carried out along the search direction. Both the simulation and experiments verify the effectiveness and high accuracy of the method. Related Articles | Metrics

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Incremental Surface Reconstruction of Unorganized Points Based on BFS WU Jun, YANG Jie, QIN Hong-xing 2008, 42 (10):  1740-1744.  Abstract ( 5546 )   Save This paper described an algorithm based on artificial intelligence widthfirstsearch algorithm for surface reconstruction of unorganized points. From the incremental computing idea, it makes full use of the state expanding characteristic of search algorithm. Recurring to octree space division, searching constraint and optimum vertex estimation, the algorithm uses initialized triangle as searching base and orientation edges as searching elements to reconstruct model surface gradually and symmetrically. The proposed algorithm supports parallel computing for visualization and does not depend much on parameters. In addition, holes and gaps can be filled optionally. The experimental results show that this algorithm is effective, robust and works well for models with arbitrary topology. Related Articles | Metrics

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Natural Polemap Dased Localization for Intelligent Vehicles WU Shun-xi, YANG Ming 2008, 42 (10):  1745-1748.  Abstract ( 5771 )   Save In order to overcome the big workload and low accuracy of measuring the polemap manually in outdoor environment, a laser radar based mapping method was presented. On the basis of this, a polemap based localization was introduced which does mapmatching using iterative closest points and can enhance the accuracy of localization. This method was tested on both synthetic and real range data collected in natural environment. The experimental results demonstrate its high accuracy, low computation and wide applicability. Related Articles | Metrics

Radiao Electronics, Telecommunication Technology

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A Low Complexity Maximum Weighted Sumrate Based Scheduling Algorithm in Multiuser MIMO System CHEN Lei, SHE Feng, LUO Han-wen 2008, 42 (10):  1749-1753.  Abstract ( 5748 )   Save To solve the problem that the dirtypaper coding based iterative waterfilling algorithm to maximize weighted sumrate has high complexity in multiuser multiinput multioutput (MIMO) system, a low complexity zeroforcing dirtypaper coding based multiuser resource scheduling algorithm was proposed. Under the transmit power constraint, the proposed algorithm combines power allocation and user scheduling. Users are selected in sequence based on the userselection parameters which are constructed using the channel state information. The proposed algorithm only needs finite repetitions, and can drop off those users with poor channel quality through the userrejection criteria. Therefore the complexity is reduced. The simulation results show that, compared to the iterative waterfilling algorithm, the proposed algorithm achieves more than 90% weighted sumrate of the iterative waterfilling algorithm under similar simulation conditions. With the increasing user number the weighted sumrate of the proposed algorithm approximates to that of the iterative waterfilling algorithm. And the complexity is reduced from the one in proportion to the square of number of users to the one in proportion to the number of users. Related Articles | Metrics

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A Novel Time and Frequency Synchronization Scheme for Orthogonal Frequency Division Multiplexing Systems GUO Yi, LIU Gang, GE Jian-hua, ZHANG Wu-jun 2008, 42 (10):  1754-1757.  Abstract ( 5448 )   Save A new training symbol was designed and a novel time and frequency synchronization scheme for orthogonal frequency division multiplexing systems was proposed. The time synchronization was accomplished by using the symmetric conjugate of the training symbol in time domain and the frequency synchronization was finished by utilizing the good autocorrelation of the training symbol in frequency domain. The simulation results show that the scheme gives very accurate estimates of symbol timing and carrier frequency offset and provides a very wide acquisition range for the carrier frequency offset. Related Articles | Metrics

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A Filter Algorithm for Improving the Calculation Speed of GPS Positioning Estimation WU Jing, MAO Xu-chu 2008, 42 (10):  1758-1761.  Abstract ( 5640 )   Save To improve the calculation speed of high accuracy positioning estimation of global positioning system（GPS）, four nonlinear filtering algorithms were described and compared in theory, which are unscented Kalman filter (UKF) and its modified algorithm, spherical unscented Kalman filter (SUKF) and its modified version. Then the modified SUKF was proposed as an optimal estimation algorithm in the standalone GPS positioning. The experimental results show that the modified SUKF achieves high positioning accuracy and improves the calculation speed significantly; it can effectively solve the realtime problem with high positioning accuracy in GPS software receiver. Related Articles | Metrics

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A Selective Video Content Encryption Algorithm Exploiting the Characteristics of H.264/AVC CABAC Entropy Encoder XIE Qiang, ZHENG Shi-bao, YU Xiao-jing 2008, 42 (10):  1762-1766.  Abstract ( 5977 )   Save In order to solve the encryption computing efficiency and flexibility issues when applying traditional data cryptographic algorithms on video content protection, this paper proposed a new selective video content encryption algorithm which exploits the characteristics of H.264/AVC CABAC entropy encoder. By introducing pseudorandomization in CABAC entropy encoder’s binary arithmetic encoding stage, the new algorithm can employ the entropy encoder itself to fulfill the basic encryption operation. In the meantime, the video content data unit being encrypted can be selected flexibly according to its importance. The experimental results show that the proposed algorithm does not impair the compression efficiency of the entropy encoder, and the encrypted video stream hides the visual characteristics of the original video content successfully. Related Articles | Metrics