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05 November 2012, Volume 38 Issue 21
    

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    Networks and Communications
  • LV Ta-Zhi
    Computer Engineering. 2012, 38(21): 1-4. https://doi.org/10.3969/j.issn.1000-3428.2012.21.001
    Abstract ( ) Download PDF ( )   Knowledge map   Save

    There is not only sensor noise, but also outlier disturbance when a robot explores in unknown environments. The traditional EKF-SLAM algorithm does not consider the impact of outlier disturbance that may lead to positioning failure. The new algorithm detects the outlier disturbance by comparing two observations result using polar coordinates. Covariance would be inflated when disturbance is detected, so that system state of uncertainty is expanded and the state quickly converges to the true value. Simulation results show that the proposed algorithm is better than EKF-SLAM both in mobile robot SLAM accuracy and robustness.

  • ZHOU Yao-Meng, WANG Bei, ZHANG Hui-Cheng
    Computer Engineering. 2012, 38(21): 5-9. https://doi.org/10.3969/j.issn.1000-3428.2012.21.002
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    The existing methods ignore multicomponent characteristics of evolution process of Internet public opinions, which leads to an unsatisfactory performance of analysis and modeling. To deal with the problem, this paper presents an evolution analysis and modeling method of Internet public opinions based on Empirical Mode Decomposition(EMD). It decomposes the evolution process of Internet public opinions by EMD, to form trend component, period component, mutation component and random component. Then it analyzes and models the evolution process of Internet public opinions by analyzing and modeling the above-mentioned components. Experiments show that the components decomposed by EMD have clear physical meanings, which can help to analyze the evolution patterns of Internet public opinions; at the same time, the method has good forecasting performance, thus is more suitable.

  • YANG De-Guo, LI Zhi, JIANG Jin-Di
    Computer Engineering. 2012, 38(21): 10-13. https://doi.org/10.3969/j.issn.1000-3428.2012.21.003
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    This paper presents a digital watermarking algorithm based on audio features and the relatively smaller values of the low frequency of DWT coefficients. The proposed algorithm analyzes the zero-cross ratio and the short-time energy of frame to select the appropriate threshold for initial discarding the high-frequency signal components of the audio frame, selecting the audio frame to be processed. The selected audio frames are stitched together and perform discrete wavelet transform, choosing the low-frequency coefficients and segmenting, using the sum binary value of the neighboring three watermark bit combination to determine the location of the watermark embedding, and make its value smaller. The proposed algorithm for blind watermark detection reduces the extraction time complexity of low-frequency components through the analysis of audio features, and improves the robustness of the watermark.

  • HAN Chi-Zhong, WANG Zhong-Sheng, JIANG Hong-Kai
    Computer Engineering. 2012, 38(21): 14-16,21. https://doi.org/10.3969/j.issn.1000-3428.2012.21.004
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    The aircraft sudden failure is a kind of random faults, which is a serious threat for the safe. To present the law of the aircraft sudden failure, this paper proposes to analyze and disclose the mechanism, the feature and procedure of the aircraft sudden failure evolution by dissipative structure theory. Based on that, it models the sudden failure evolution model on aircraft via time varying entropy and time varying frequency band energy distribution, and then it simulates the model by the surge of aero-engine. The results suggest that the entropy and the frequency band energy distribution of the dissipative structure are useful to present the procedure and the feature of the aircraft sudden failure evolution.

  • LI Chu-Zhi, WANG Xian-Min
    Computer Engineering. 2012, 38(21): 17-21. https://doi.org/10.3969/j.issn.1000-3428.2012.21.005
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    A dynamic graph software watermarking algorithm based on the m-n Variable Carrying Rule(VCR) is proposed towards the drawback of the slow recovery rate and the data expansion of software watermarking sharing algorithm. This algorithm takes advantage of the correspondence of watermarking, m-n Variable Carrying Number(VCN), permutation number and Permutation Graph(PG) to implement the watermarking sharing and encoding. When the watermarking is embedded, it uses the VCR to share the watermarking as VCN, and then convertes them into a permutation number with a perfect Hash function, at last encodes them as the PG and embeds it in the program execution code. The watermarking extracting is the reverse process of the watermarking embedding. Experimental analysis shows that this algorithm decreases the program load and the watermarking recovery time complexity and improves the watermarking steganography and error correction capability.

  • TAO Ye, JIANG Yu-Ji, LIANG Xu-Wen
    Computer Engineering. 2012, 38(21): 22-25,29. https://doi.org/10.3969/j.issn.1000-3428.2012.21.006
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    Combined Input and Crosspoint Queued(CICQ) switch fabric can effectively isolate input ports and output ports because of crossspoint buffers. Due to this fabric, it can reduce the complexity of the scheduling algorithm. This paper researches the CICQ switch and a lot of different types of scheduling algorithms for CICQ switch and proposes an algorithm based on flow control, called FCSA. Extensive simulation results using OPNET show that the algorithm achieves a satisfactory delay and throughput performance under both uniform and a broad class of non-uniform traffic patterns. Additional simulation results in the satellite onboard switch also using OPNET show that the proposed algorithm is suitable to apply to implement onboard satellite switch with different bursty traffics, because of its low complexity and capability in hardware implementation.

  • TIAN Feng-Chun, YAN Jia, HE Qiang-Hua, CHEN Yue, FENG Jing-Wei, GU Feng-Fei, XU Pan
    Computer Engineering. 2012, 38(21): 26-29. https://doi.org/10.3969/j.issn.1000-3428.2012.21.007
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    For the problem of background interference in wound infection detection by electronic nose, this paper proposes a background interference elimination algorithm of Independent Component Analysis(ICA) with reference vector. It employs ICA to decompose signals of the sensor array and extract independent components, and discriminates useful sources and background interference through the correlation between the independent components and a reference vector. Then neural network classifier is used for discrimination. Experimental results show that the algorithm can effectively eliminate the electronic nose background interference and improve the recognition accuracy rate of wound infection.

  • CHEN Hua-Shan, WANG Yi, LIU Xian-Cheng, ZHOU Juan
    Computer Engineering. 2012, 38(21): 30-32. https://doi.org/10.3969/j.issn.1000-3428.2012.21.008
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    Aiming at the abnormal data real time filtering problem, this paper puts forward a Savant middleware based on abnormal data processing algorithm. According to the functions and characteristics of the Savant middleware, designs the exception filter module, adds storage unit and uses queue method to filtrate the abnormal data. It proves the effectiveness of the algorithm by the storage management storage simulation experiment, and shows that the algorithm has a good filtering effect, it is suitable for abnormal data processing of large-scale data set.
  • TUN Gong-Hua, LIU Guo-Hua
    Computer Engineering. 2012, 38(21): 33-35. https://doi.org/10.3969/j.issn.1000-3428.2012.21.009
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    In order to improve the uncertainty of time sequence query efficiency, on the base of uncertainty time series data set modeling, this paper presents three kinds of specification method from uncertain time series to certain time series, including probability maximum method, mixed specification method and mean value method, and gives specification process. Experimental result shows that three kinds of specification method can reduce the uncertainty of the time series, provide basis for its similarity matching, search and query operation.
  • LIU Hai-Chao, WEI Ru-Xiang, JIANG Guo-Ping
    Computer Engineering. 2012, 38(21): 36-39. https://doi.org/10.3969/j.issn.1000-3428.2012.21.010
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    For the excessiveness of operating factors and multi-correlation of variables in software cost estimation, this paer proposes a software cost estimation method based on Partial Least Squares Regression(PLSR). After the variables are weighted, an integrated index named analogue deviation is defined to describe the approximation of data samples. Then an adaptive weight is assigned to sample according to the approximation, and the optimal partial least squares latent variables and weight parameters are calculated by traversal searching. Experimental results show that the prediction error is reduced by 73.61% and 32.34% than multiple linear regression and PLSR respectively.
  • DENG Feng, LI Mei-Yi, HE Cheng
    Computer Engineering. 2012, 38(21): 40-44. https://doi.org/10.3969/j.issn.1000-3428.2012.21.011
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    Based on the analysis of the Secondary Namenode mechanism, Backup Node mechanism and Facebook Avatar mechanism, an improved scheme of Avatar is proposed to solve the Single Point of Fault(SPOF)of Namenode existing in Hadoop Distributed File System(HDFS) which is a distributed file system of Hadoop. Client request is transmitted from the master node to standby node, and the Zookeeper is used to take over failover. And then the SPOF of Namenode is solved. The correctness of this program is verified by Petri net modal in theory and the quantitative analysis of its availability is conducted by storage network fault repairing model based on finite element method. Experimental result demonstrates the advantages of this program which are nonvolatile, fast failover and automatic failover.
  • LI Hai-Feng, ZHANG Ning
    Computer Engineering. 2012, 38(21): 45-48. https://doi.org/10.3969/j.issn.1000-3428.2012.21.012
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    Maximal frequent itemsets is suitable for stream mining, which store most of the information contained in frequent itemsets using less space. This paper focuses on mining maximal frequent itemsets incrementally over streams under landmark model. It designs a simple and compacted data structure to effectively maintain a dynamically selected set of itemsets for quickly node search and pruning. Experimental results on the MUSHROOM and BMS-POS datasets show that this method has higher mining efficiency.
  • LIU Jian-Hua, WANG Min-Chao, WU Xing
    Computer Engineering. 2012, 38(21): 49-52. https://doi.org/10.3969/j.issn.1000-3428.2012.21.013
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    This paper researches the elastic structure of the cloud program in the cloud computing environment. It combines the Anytime algorithm, an elastic billing model and a Service Level Agreement(SLA) framework in Software as a Service(SaaS), implements an elastic structure cloud program which is based on the wavelet algorithm and presents the working process and state transition diagram. Analysis result shows that the elastic structure program can control program iterative times according to user demand, better satisfy the needs of clients.
  • WANG Feng-Mei, HU Li-Xia
    Computer Engineering. 2012, 38(21): 53-55,62. https://doi.org/10.3969/j.issn.1000-3428.2012.21.014
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    Data missing is a common problem in data mining and data analysis process, it can lead to reliable decision-making if it is deleted with the cases directly. An imputation method of solving the missing data is put forward, which is based on association rule. In this method, the rules are classified by the rules’ consequent, and then calculate the similarity of constrained rules cases’ items and missing cases’ items, impute the missing value with the most similar rule’s item. Experimental results show this method has higher imputation accuracy.
  • LENG E-Jun, LIANG Chang-Yong, LIU Jing, LIU Wen-Xing
    Computer Engineering. 2012, 38(21): 56-58,66. https://doi.org/10.3969/j.issn.1000-3428.2012.21.015
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    Data sparsity influences the recommendation quality of collaborative filtering algorithm. To address this problem, a new hybrid collaborative filtering algorithm based on neighbor rating imputation is proposed. The dimensions of original rating matrix are reduced by Principal Component Analysis(PCA), which can reduce the computational complexity. Singular Value Decomposition(SVD) is used to impute missing ratings of the neighbors, which can alleviate the data sparsity. Experiments are carried out on MovieLens dataset, and the results show that the algorithm has higher the recommendation efficiency.
  • YANG Li, TUN Zhi-Chao, WANG Yan-Chun
    Computer Engineering. 2012, 38(21): 59-62. https://doi.org/10.3969/j.issn.1000-3428.2012.21.016
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    In satellite network, there are task conflicts which arise from communication application between several satellites and a satellite at the same time. In order to solve the problem, this paper proposes a dynamic priority-based scheduling algorithm. In the established satellite communication task model, the urgency of the task is used to express time constraints both deadline for tasks and spare time. The task urgency is used to control to the influence of the task priority by adjusting the parameter p according to the characteristics of the satellite network. A conflict model is built by STK scene to do simulation, and experimental results show that the algorithm enhances task completion rate by 3.9% than FCFS algorithm.
  • ZHOU Ren-Xing, LIU Lei-Bei, YIN Shou-Yi, WEI Shao-Jun
    Computer Engineering. 2012, 38(21): 63-66. https://doi.org/10.3969/j.issn.1000-3428.2012.21.017
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    A Bitmap index based Reliable Data Transmission(BRDT) protocol applied in Wireless Sensor Network(WSN) which demands real-time upstream massive data transmission, is proposed. In the BRDT, data generated by the sensor nodes are transferred through several iteration cycles. Each iteration cycle contains a retransfer-free data flow and an index packet transmission through back channel to recover lost packets. The performance of the BRDT is obtained from simulation and is verified on the Z-EYE system, results show that compared with the RMST, the BRDT has less service demanding on lower layer, the BRDT has better performance improvement than the widely used NACK retransfer method in high packet loss rate networks, and the BRDT has better transmission efficiency than the PSFQ in the same test situation.
  • DIAO Hua-Feng
    Computer Engineering. 2012, 38(21): 67-69,73. https://doi.org/10.3969/j.issn.1000-3428.2012.21.018
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    For computing the minimum connected r-hop k-dominating set, a heuristic algorithm is proposed based on greedy strategy about node degrees. It starts with an initial solution containing all nodes in the network, from which it repeatedly selects a node with minimal degree and decides whether to remove the node from current feasible solution according to connectivity. The size of feasible solution is reduced gradually, until all nodes are processed. Its time complexity is analyzed in Unit Disk Graph(UDG). The numerical experimental results show that the new algorithm generates smaller connected r-hop k-dominated set and achieves more stable performance than existing related algorithms.
  • CAO Jia-Lin, CHEN Xu-Bin, CHEN Bin, CENG Xiao-Xiang
    Computer Engineering. 2012, 38(21): 70-73. https://doi.org/10.3969/j.issn.1000-3428.2012.21.019
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    In order to overcome the fast fading channels which are difficult to be estimated and the considerable Inter Carrier Interference(ICI) in highly mobile Orthogonal Frequency Division Multiplexing(OFDM) system, an iterative channel estimation and ICI mitigation algorithm are proposed. It uses feedback information from the channel decoder. Discrete Fourier Transform(DFT) based channel estimation is employed and linear approximation is used to mintage the ICI with low complexity. Simulation results show that the method allows reliable reception with normalized Doppler frequency at 10%~15%.
  • HOU Gui-Sheng, TUN Xiao-Bei
    Computer Engineering. 2012, 38(21): 74-77. https://doi.org/10.3969/j.issn.1000-3428.2012.21.020
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    Aiming at routing problems of Data-centric Storage(DCS) in Wireless Sensor Network(WSN), this paper proposes a Tree Label System(TLS) based distributed routing algorithm. The algorithm organizes network nodes into a spanning tree whose root is a certain reference node in the network. For data routing, it only needs to compare the destination node’s label with neighbor nodes’ labels and select appropriate forwarding nodes based on the results. Analysis and simulation results show that the algorithm routing space cost is low, and its routing efficiency is high, and its generated path is close to the shortest path.
  • ZHONG Yuan, FANG Wei-Wei, YANG Fang-Na, LIANG Xiang-Min, HUANG Shi
    Computer Engineering. 2012, 38(21): 78-80,85. https://doi.org/10.3969/j.issn.1000-3428.2012.21.021
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    The mobile Worldwide interoperability for Microwave Access,(WiMAX) network test system is developed for the terminal device of WiMAX. It is an integrated network test system for network and geographic information data acquisition, real-time display, historical display and analysis features. Number of performance indicators of the WiMAX network are comprehensively tested and displayed as a combination of the geographical data and network performance data. The system covered with WiMAX network on the Shuohuang Railway is tested, results show that the test system achieves the desired objectives.
  • HE Lin, LIN Feng, ZHOU Ji-Liu
    Computer Engineering. 2012, 38(21): 81-85. https://doi.org/10.3969/j.issn.1000-3428.2012.21.022
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    To improve the utilization of Delay Tolerate Mobile Sensor Network(DT-MSN) and to deal with the networks deployment issues, this paper proposes a decision condition about whether the global network has a sample network of isomorphic by applying the sub-graph expansion under a specific scenario, and then proposes a algorithm about clustering the sensors that are connected with maximum times by using minimum spanning tree on condition of existing sample networks. The method can build an isomorphic network between the sample network and global network at data flow. Simulation is used to prove this scenario existing the isomorphic networks, and establishes a sample network. Result shows the sample network scenario can replace the global network to assess network’s performance. So it can offer reliable evaluation reports before setting a large scenario, and have an important practical application.
  • ZHANG Pan-Suo, LI Guang-Beng, LIU Dong-Feng
    Computer Engineering. 2012, 38(21): 86-88. https://doi.org/10.3969/j.issn.1000-3428.2012.21.023
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    This paper researches that the source and destination are equipped with multiple antennas, the relay only has a two-hop relay system with a single antenna. Quasi-orthogonal Space-Time Block Code(OSTBC) and MRC are employed at source, and destination, respectively, to achieve spatial diversity. To reduce the implementation complexity of the relay, the fixed-gain amplify-to-forward relay protocol is used. New exact expressions for outage probability and average bit error rate are derived in Nakagami-m fading environments. Numerical comparison results between Monte Carlo simulations show the accuracy of the theoretical expressions.
  • WANG Zhen-Chao, SUN Bo, WANG Fang
    Computer Engineering. 2012, 38(21): 89-92. https://doi.org/10.3969/j.issn.1000-3428.2012.21.024
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    The correlation peak located in the initial position of Cyclic Prefix(CP) in training symbol has the similar intensity with the one at the correct timing position, which causes the timing error in Orthogonal Frequency-Division Multiplexing(OFDM) preamble-aided synchronization algorithms. To overcome the problem, a new synchronization training symbol is formed with the conjugated symmetrical training symbol by multiplying Pseudo-Noise(PN) weighted factor, this paper proposes a new timing metric as well as the corresponding algorithm of improved timing synchronization and frequency offset estimation based on the new structure of training symbol. The proposed algorithm eliminates cyclic prefix correlation peak effectively so as to overcome the inaccurate timing and improve the accuracy of frequency offset estimation by utilizing autocorrelation of the pseudo-random weighted factor. Simulation results show that the proposed algorithm not only improves the synchronization performance, but also reduces the computational complexity.
  • ZHOU Zhe-Shuai, FU Cong-Xi, WANG Xu-Ying, WANG Kai-
    Computer Engineering. 2012, 38(21): 93-96. https://doi.org/10.3969/j.issn.1000-3428.2012.21.025
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    In order to quantitatively analyze the impact of communication support capability on early-warning detection efficiency under electronic jamming condition, based on the study of the air-raid targets searching process, this paper builds the detection probability calculating model of target indicating radar by evaluating the jamming efficiency of the air intelligence informing communication. Combined with the typical combat scenario, analysis of examples simulation is done and the results show that the jamming effect of using airborne jamming is better than using subgrade jamming on communication and the target indicating error caused by early-warning information does not affect the improvement of early warning detection capability.
  • CHENG Wen-Fei, TAN Xiao-Ban, XU Feng
    Computer Engineering. 2012, 38(21): 97-99,106. https://doi.org/10.3969/j.issn.1000-3428.2012.21.026
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    The vast majority of multicast route protocols are achieved by multicast tree, which ignore some available transmissions of neighbour links after establishing multicast tree. The procession of establishing multicast tree spends much time and space resource, and the whole information of the network is needed. In order to improve the QoS, greedy strategy is added to Mesh networks route, does not establish multicast tree and let the most efficient node send data packet in local area. The protocol can make use of the efficient links fully with local area information between neighbour nodes, and distribute achievement. Simulation experimental results show that the protocol has more improvement than Pacifier protocol.
  • LI Guo-Han, WANG Ge-Ren, JIN Hu
    Computer Engineering. 2012, 38(21): 100-102. https://doi.org/10.3969/j.issn.1000-3428.2012.21.027
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    In order to achieve the sub-carrier number estimation of Orthogonal Frequency Division Multiplexing(OFDM) signal, a method based on Kolmogorov-Simirnov(KS) test statistics is proposed for normality test. It is proved that the Gaussianity of DFT processor output on reconnaissance terminal is weak when DFT points match with that of transmitter. The results of simulation and analysis show the method can be employed to distinguish Gaussian signal from non-Gaussian signal, and achieve sub-carrier number estimation of OFDM.
  • LIU Xiao-Meng, LIAO Cong, HONG Meng-Rou
    Computer Engineering. 2012, 38(21): 103-106. https://doi.org/10.3969/j.issn.1000-3428.2012.21.028
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    A joint timing and carrier phase estimation algorithm is proposed for the synchronization problem of Continuous Phase Modulation (CPM) based on decision data. After using Laurent representation to express CPM signals, Timing Error Detector(TED) and Phase Error Detector (PED) are got from the joint likelihood function of timing and carrier phase. After finding the instant gradient, the estimated timing and phase value is recovered by iteration computation. After analyzing the common binary partial response CPM signals such as PCM/FM, the implementation scheme of joint timing and carrier phase estimation algorithm is designed. Simulation result shows that the proposed algorithm is suited for binary partial response CPM signals. The timing and carrier phase error variance curve is close to the theoretical limit.
  • LIU Chun-Xiao, CHANG Gui-Ran, GU Jie, SUN Li-Na
    Computer Engineering. 2012, 38(21): 107-109,113. https://doi.org/10.3969/j.issn.1000-3428.2012.21.029
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    By considering the number of gateways and gateway load balancing, this paper proposea a force-based greedy heuristic clustering algorithm. On this basis, it improves the hybrid Particle Swarm Optimization(PSO) algorithm and gives a gateway placement algorithm for Wireless Mesh Network(WMN). Simulation results show that the algorithm can effectively achieve the load balancing among gateways with less number of gateways, and improve the network throughput and the network performance.
  • TU Xin-Yong, CHANG Dun, TU Jiang
    Computer Engineering. 2012, 38(21): 110-113. https://doi.org/10.3969/j.issn.1000-3428.2012.21.030
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    In consideration of the complexity and diversity of the smart distribution business, a Quality of Service(QoS) mechanism that is more flexible and efficient than that of tradition is needed. The smart distribution service characteristic is analyzed. WRED_gentle algorithm, an improved Weighted Randomly Early Detection(WRED) algorithm, is proposed in active queue management. By the modeling of meter reading application and the power distribution automation application, noWRED, WRED, and WRED_gentle algorithm are simulated on OPNET. Results indicate that the performance of network delay, throughput and link rate is obviously improved after adopting the WRED_gentle, which guarantees the QoS requirements of the smart distribution communication network.
  • LIN Jing-An, CHU E-Qiang
    Computer Engineering. 2012, 38(21): 114-118,122. https://doi.org/10.3969/j.issn.1000-3428.2012.21.031
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    In order to quickly and correctly transfer data groups, while extending network life, this paper puts forward an Ad Hoc network routing protocol based on Ant Colony Optimization(ACO) named ABEAR. It applies cross-layer design idea, and uses information consistence, wireless channel using conditions and node’s rest engery to select next hop. According to communication situation between nodes, some idle nodes are made into sleeping, so that engery can be saved. ABEAR protocol is realized by C++ and OTcl language in NS2 platform.
  • GENG Ling, ZHENG Wei-Wei, MA Wei-Dong
    Computer Engineering. 2012, 38(21): 119-122. https://doi.org/10.3969/j.issn.1000-3428.2012.21.032
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    This paper proposes an identification method which can achieve traffic identification with great efficiency and speed based on connectivity degree of nodes. P2P traffic is distinguished from non-P2P traffic in network by associating the attributes of the two kinds of traffic which are obtained by analyzing the experimental results according to connectivity degree features of different P2P traffic. The facts that traffic attributes of P2P downloading are similar and traffic attributes of P2P downloading are different from traffic attributes of P2P streaming media are proved by analyzing the behavioral properties of P2P downloading and P2P streaming media. Experimental results show that the proposed method has good performance in instantaneity and accuracy.
  • SHUAI Fei, LI Dun-Quan, MO Wei
    Computer Engineering. 2012, 38(21): 123-125. https://doi.org/10.3969/j.issn.1000-3428.2012.21.033
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    When D-S evidence theory is applied to assess the security level of information security products, it may produce the whole conflict paradox,1 confict paradox and 0 confict paradox. To solve this problem, this paper designs an evidence combination method based on evidence support consistency classification. It classifies the evidence according to support consistency, discounts evidence according to the degree of importance of expert advice, and combines D-S combination method and weighted average method to combine classified evidences. Analysis results show that the method has higher applicability and lower computational complexity.
  • JIAO Bei, LI Hui, HUANG Cheng-Dong, LI Wei
    Computer Engineering. 2012, 38(21): 126-128,132. https://doi.org/10.3969/j.issn.1000-3428.2012.21.034
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    D-S evidence theory can be used for uncertain information decision fusion effectively, but there is a problem of cannikin effect. This paper proposes an information security evaluation method based on aggregation of variable weight evidence. It adjusts state variable weight vector adaptively in accordance with the security risk degree of indexes corresponding to evidences, distributes new weights depending on the approximation degree between evidence and low security level, and realizes aggregation using DS rule. Comparison experiments confirm that the proposed method can acquire more reasonable evaluation results.
  • LI Qiang-Peng, ZHENG Lian-Qing, ZHANG Chuan-Rong, YANG Tong
    Computer Engineering. 2012, 38(21): 129-132. https://doi.org/10.3969/j.issn.1000-3428.2012.21.035
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    Traditional attack graphs usually neglect the vulnerability correlation in network, and large-scale attack graphs are too complex. To solve the problems above, an optimization method for attack graph based on Vulnerability Exploit(VE) correlation is proposed. It eliminates the redundancy of attack graph by using the correlation between VE, and optimizes attack graph by transversal and vertical correlation, after pretreatment of the attack graph are generated. Experimental results show that the method can optimize the expression of attack graph better, and lay a good foundation for network security evaluation.
  • ZHOU Ke, DAI Yong, FAN Liang
    Computer Engineering. 2012, 38(21): 133-137. https://doi.org/10.3969/j.issn.1000-3428.2012.21.036
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    Single-mode password authentication has kinds of disadvantages, like single input mode and low security. This paper proposes a method to disordered fusion input for heterologic code. It builds fusion mechanism based on hardware generating of heterologic model code, gives normalized form of heterologic model code information, and designs the corresponding algorithm, like different pre-processing and classification of password code, for different model information. Disordered fusion of heterogeneous model code is implemented through public unit of heterologic code. Application of disordered fusion based on password keyboard model and black box model show that the mechanism is suitable for multi-mode password input system.
  • TUN Xue-Ken, TUN Jin, LIU Jin, TUN Jian-Guo
    Computer Engineering. 2012, 38(21): 138-140,144. https://doi.org/10.3969/j.issn.1000-3428.2012.21.037
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    Steganography on wavelet domain against statistical based on Human Visual System(HVS) embeds secret information by decreasing the absolute value of wavelet coefficients, so it dramatically increases the probability to zero of wavelet coefficients. In order to analyze this steganography method, this proposes steganalysis method of wavelet coefficient statistical feature quantity. By analyzing the wavelet coefficients histogram of cover-images and stego-images, and calculates wavelet coefficients statistical feature quantity of images, it judges the presence of secret information, so that the steganalysis method is realized. Theory analysis and experimental results show that the method can announce the presence of hidden information.
  • WANG Gao, CHEN Ze-Mao, CHEN Shuang-Shuang
    Computer Engineering. 2012, 38(21): 141-144. https://doi.org/10.3969/j.issn.1000-3428.2012.21.038
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    In order to ensure the confidentiality of information sharing in Local Area Network(LAN), a multi-level security model for LAN based on BLP model named MLS-LAN is proposed. It estimates the security-level of dynamic information resources by introducing security-level calibration facility in LAN, and it uses access authentication facility and access control facility to define access authentication, information sharing and communication relationship control rules, so that secure sharing for multi-level information in LAN is realized. Theoretical results show the model can provide reliable access control to information sharing and enhance its security.
  • GAO Dong-Hui, DONG Beng-Beng, TIAN Yu-Bei, ZHOU Hao-Tian
    Computer Engineering. 2012, 38(21): 145-147. https://doi.org/10.3969/j.issn.1000-3428.2012.21.039
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    Particle Swarm Optimization(PSO) algorithm is difficult to deal with the problems of premature and local convergence. In order to solve the problems, an Improved PSO with Wavelet Mutation(IPSOWM) algorithm is proposed. In IPSOWM, mutation operator is undertaken by selecting particles with certain small probability so as to overcome the PSO’s drawback of occurring premature convergence and trapping in the local optima. Experimental results on benchmark functions show that the performance of IPSOWM algorithm is obviously superior to that of the other PSO algorithms in references, including convergence precision, convergence rate and stability.
  • MENG Xian-Meng, LING Pei-Liang, GONG Xin-He
    Computer Engineering. 2012, 38(21): 148-152. https://doi.org/10.3969/j.issn.1000-3428.2012.21.040
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    For the important role of techniques and tactics analysis on the training and competition of the net antagonistic event competitions project, it is the first time for the study to build the Intelligent Decision Support System based on Data Mining(DM-IDSS) of the project in techniques and tactics analysis. The integrated mechanism of DM-IDSS, decision-making inference as well as design and implementation are introduced. Results of case study show that the knowledge extracted by DM-IDSS from history data can provide valuable suggestions and directive function for tactics intelligence decision support of the net antagonistic event competitions project, and its interence results have well accuracy.
  • WANG Rui, ZHOU Chi, LI Xiao
    Computer Engineering. 2012, 38(21): 153-156,160. https://doi.org/10.3969/j.issn.1000-3428.2012.21.041
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    In addition to the main content, most Uighur Web contain noises such as navigation panels, advertisements which are not related to the main content. To improve the efficiency of security detection, this paper presents a content extraction algorithm of Uighur Web based on Web text correlativity, and designs the model of text density and content scale to improve the algorithm. Experimental result shows that this algorithm can extract the main content from the Uighur Web efficiently.
  • ZHANG Lin-Lin, JIANG Min, TANG Xiao-Wei
    Computer Engineering. 2012, 38(21): 157-160. https://doi.org/10.3969/j.issn.1000-3428.2012.21.042
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    Eye movement is easily influenced by head posture change, external simulation interference and actual light conditions. The existing algorithms have low accuracy and robustness. An eye tracking algorithm based on blinking correction Kalman filter is proposed. Eye region of face image is detected using vertical and horizontal integral projection function. It uses the color entropy of eye region to eliminate uncorrelated factors, precisely locates the position of pupil. The eye region is tracked in real time by Kalman filter, and eye blink detection is combined to revise eye tracking. Experimental results show that the algorithm has high accuracy and good real-time.
  • ZHOU Yan, LIU Tao, CHANG Li
    Computer Engineering. 2012, 38(21): 161-163,167. https://doi.org/10.3969/j.issn.1000-3428.2012.21.043
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    Aiming at the problem that since the standard Matching Pursuit(MP) algorithm tends to cause enormous calculation quantity when searching for the optimal atoms, this paper proposes a scheme of Matching Pursuit algorithm based on Immune Algorithm(IA-MP). This algorithm adopts immune cloning optimization mechanism to search for the optimal atoms, using the population scale of antibodies to control the size of redundant dictionary, and choosing real cross and nonsymmetrical mutation to ensure the completeness of dictionary. Simulation results show that, compared with the standard MP and Genetic Algorithm-Matching Pursuit(GA-MP) algorithms, IA-MP algorithms can obviously reduce the matching pursuit calculation quantity, and the performance of this algorithm is more stable, in addition, this algorithm has high signal reconstruction accuracy.
  • WANG Min-Cha, ZHANG Ru-Bei
    Computer Engineering. 2012, 38(21): 164-167. https://doi.org/10.3969/j.issn.1000-3428.2012.21.044
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    Aiming at the obstacle avoidance problems of the Unmanned Surface Vessel(USV) in complex marine environment, an algorithm of obstacle avoidance based on the perception of local environment——Nearness Diagram(ND) method is introduced. Combining with the characteristics of USV’s high-speed and the jumping on speed control of ND method, this paper proposes fuzzy theory to smooth the output of speed to improve the ND method. The improved method reduces errors of dangerous avoid action caused by inertia of the USV, and improves its security. Simulation results on VxWorks system show that the improved fuzzy ND method enables USV to reach the target point and avoid obstacles more accurately and quickly in complex environment.
  • HU Feng-Song, CAO Xiao-Yu
    Computer Engineering. 2012, 38(21): 168-170,174. https://doi.org/10.3969/j.issn.1000-3428.2012.21.045
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    Aiming at the problem that speaker’s feature coefficients have poor robustness in noise environment, this paper proposes an auditory cepstral coefficient for speaker recognition. It analyzes the working mechanism of the human auditory model, simulates the auditory model of human ear cochlea by Gammatone filter banks replaces the traditional triangular filter banks. Based on the nonlinear signal processing capability of human auditory model, exponential compression is used instead of the fixed logarithm compression. Simulation experiment is conducted based on Gaussian Mixed Model(GMM) recognition algorithm. Experimental results show that the auditory feature has better noise robustness than Mel Frequency Cepstral Coefficient(MFCC) and Linear Prediction Cepstral Coefficient(LPCC).
  • DIAO Yu-Juan, LIU Qing-Chao
    Computer Engineering. 2012, 38(21): 171-174. https://doi.org/10.3969/j.issn.1000-3428.2012.21.046
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    Aiming at the problem that the low classification accuracy rate of small sample in machine learning, this paper proposes a weighted integration of multiple classifiers method based on Hybrid Multiple Distances(HMD) measurement. In this method, three measure methods are combined, and the output of each classifier is integrated by weighted majority voting. It designs the mixed distance measure weighted method, and uses the weighted voting combination rules to integrate the classifier output results. Experimental results show that this method has good robustness and high classification accuracy.
  • XU Chen, CAO Hui, DIAO Xiao
    Computer Engineering. 2012, 38(21): 175-177. https://doi.org/10.3969/j.issn.1000-3428.2012.21.047
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    For high computational complexity of Support Vector Machine(SVM), this paper uses normalized and Principal Component Analysis(PCA) transform algorithm for voice data pretreatment, combining K-fold cross validation with grid searching in speech recognition. Analysis results show that compared with GA and PSO, this method can effectively improve the SVM parameters optimization efficiency when the recognition rate is basically unchanged.
  • LI Jie, BANG Ru-Yang, YUAN Chang-An, WANG Ren-Min, LIANG Jun-Chao
    Computer Engineering. 2012, 38(21): 178-181. https://doi.org/10.3969/j.issn.1000-3428.2012.21.048
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    Under the threshold high or low, Sobel operator will form the fake edge and the missing of edge. In order to overcome it, this paper proposes a new method which combines Bacterial Foraging Optimization(BFO) algorithm with Otsu algorithm, makes use of global optimization ability of BFO algorithm, uses the Otsu algorithm as the fitness function to search the best threshold, and automatically detects image edges. Experimental result shows that the method improves the retrieval speed of threshold and makes better effect of edge segmentation.
  • LIU Meng-Fei, LIU Xi-Yu
    Computer Engineering. 2012, 38(21): 182-184,188. https://doi.org/10.3969/j.issn.1000-3428.2012.21.049
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    In order to alleviate user fatigue and apply the interactive Genetic Algorithm(GA) into complicated optimization problems, this paper presents interactive GA based on Semi-supervised Support Vector Machine(S3VM), which is used to establish the surrogate model. According to the geometry of the underlying marginal distribution from both labeled data and unlabeled data, it derives a data-dependent kernel in order to establish S3VM. Self-training method is employed for batch selecting the high reliable unlabeled samples. The method is applied to relevance feedback image retrieval, and experimental results show it is effective to accelerate the evolution of the convergence and increases the optimization success ratio.
  • WANG Meng
    Computer Engineering. 2012, 38(21): 185-188. https://doi.org/10.3969/j.issn.1000-3428.2012.21.050
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    The dynamic backtracking algorithm keeps its assigned value for each variable when it backtracks. However, it becomes inefficient when it comes to the constraint satisfaction problems that do not consist of sub problems. To solve the problem, this paper applies graph partitioning to dynamic backtracking. The main idea is to divide all the variables into several sets using graph partitioning. When it back tracks, it gives up the values of the variables that are in the same set with the culprit variable, instead of keeping all the values. Experimental results show that the new method has higher efficiency on the random satisfaction problems.
  • BIAN Zhi-Guo, TAO Yuan-Yuan
    Computer Engineering. 2012, 38(21): 189-192,196. https://doi.org/10.3969/j.issn.1000-3428.2012.21.051
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    Due to the various types of dynamic changes of background and foreground characteristics during object tracking in infrared image sequences, this paper proposes an object tracking algorithm of multi-feature fusion based on binary classification. The scene is classified into object and background region based on characteristics such as intensity, texture and grad orientation. The likelihood map is combined with the weights corresponding to classification performance respectively. A re-sampling particle filter is employed to estimate the object state. Experimental results show that the proposed algorithm is robust to environmental illumination and partial occlusions.
  • WANG Ai-Beng, JIANG Li
    Computer Engineering. 2012, 38(21): 193-196. https://doi.org/10.3969/j.issn.1000-3428.2012.21.052
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    For the standard Back Propagation(BP) algorithm usually has the limitations of slow convergence and local extreme values, a new BP neural network learning algorithm based on Particle Swarm Optimization(PSO) is proposed. The main idea of the model is to modify weight and threshold using PSO based on the weight adjustments of gradient descent method in BP algorithm. It evaluates the model by using simulation test of five typical complex functions and compares it with other two models including standard BP network and traditional PSO based BP network. Experimental results show that it can overcome the limitations of slow convergence and local extreme values for BP network and perform better than other two kinds of optimized BP network models.
  • BANG Cheng, JIAN Long-Hua, DIAO Zhi-Wei, ZHOU Guo-Dong
    Computer Engineering. 2012, 38(21): 197-201. https://doi.org/10.3969/j.issn.1000-3428.2012.21.053
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    To scientifically compare the effect of structured information and parsers on kernel-based relation extraction, a comparison method based on random approximate test is proposed. It gives two relation extraction results for different settings, samples are produced repeatedly using random label exchange from re-sampling techniques, and significant tests are conducted by calculating the performance differences between these samples. Experimental results show that dynamic relation tree is the best structured information, and the performance of Charniak and Berkeley are better than Stanford.
  • HUANG Yong-Hui, CHANG Diao-Wei, ZHANG Meng-Xin
    Computer Engineering. 2012, 38(21): 202-205. https://doi.org/10.3969/j.issn.1000-3428.2012.21.054
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    To improve the quality of automatic image annotation. A image annotation method combined of feedback log and mixture probabilistic model is proposed in this paper. It calculates the similarity of words by using ontology semantic-web, analyzes the feedback logs by using these similarity and gets the correlation of words in this application, combines the correlation and low-level image features to annotation images. Experimental results show that this method can achieve good recall ratio and precision ratio.
  • XIAO Qi, HAN Guo-Jiang, XIAO Jian-Xu
    Computer Engineering. 2012, 38(21): 206-209,213. https://doi.org/10.3969/j.issn.1000-3428.2012.21.055
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    According to the existing problems of image restoration in the speed and the quality, this paper presents an image restoration algorithm based on combined dictionaries and constrained optimization. A new constrained optimization model representing the image restoration problem is created. The objective function of it is composed of the l2 data fidelity term and dual l1 regularized term. Then the alternating minimization technology is used to decompose the constrained optimization model into several subproblems to be solved, and the proximal operators are introduced to solve denoising subproblems. Experimental results demonstrate the effectiveness of the presented image restoration algorithm, and compared with some similar state-of-the-art algorithms, it shows better restored results and faster speed.
  • WANG Wei-Wei, TONG Hua-Feng, XUAN Guo-Rong, SHI Yun-Qiang
    Computer Engineering. 2012, 38(21): 210-213. https://doi.org/10.3969/j.issn.1000-3428.2012.21.056
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    Aiming at the problem of choosing DCT coefficients blocks in data hiding, this paper proposes a lossless data hiding method for JPEG images based on minimum entropy. Utilizing the histogram pairs method, data are embedded into the low-middle frequency quantized coefficients of DCT blocks with the minimum forecast entropy. Without recording location map of selected blocks, hidden data can be extracted blindly and the original image can be reconstructed with no distortion. Experimental results show that the Peak Signal to Noise Ratio(PSNR) of this method is higher than other methods.
  • ZHANG Xiao-Juan, LI Zhong-Ke, WANG Xian-Ze, LV Pei-Jun, WANG Yong-
    Computer Engineering. 2012, 38(21): 214-217. https://doi.org/10.3969/j.issn.1000-3428.2012.21.057
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    In the optical non-contact measurement process, the reconstruction of complex object depends on the registering of point clouds. Aiming at this problem, this paper proposes a registration method of point clouds data based on Genetic Algorithm(GA). At different views, according to the same change trend of curvatures of the topology at same surface about point clouds of scanning beam, based on GA, the overlapping region is identified and transition matrix is directly extracted, and the registration is completed. Experimental results show that the method has better registration performance.
  • GUO Cheng-Xiang, GAO Hua-Ling, YANG Jian-Zhong, LI Hong-Heng
    Computer Engineering. 2012, 38(21): 218-220. https://doi.org/10.3969/j.issn.1000-3428.2012.21.058
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    The denosing performance of standard median filtering algorithm is poor. Aiming at this problem, this paper proposes a denoising algorithm based on noise detection. It uses four directions of the nuclear convolution to distinguish noise point and signal points from image pixels, diretly outputs the signal points, and processes the noise point. If the minimum neighborhood of the noise point has signal points, the signal points is uesed to median flitering; Otherwise, it expands the range of the neighborhood in value processing. Experimental results show that the algorithm not only can effectively removes image noise, but also can better protect the edge, which enhances the recovery image clarity.
  • LEI Yu-Hai, CHEN Yan-Fei, WANG Chun-Ji, SHU Zhen-Min
    Computer Engineering. 2012, 38(21): 221-225,236. https://doi.org/10.3969/j.issn.1000-3428.2012.21.059
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    This paper proposes an image compression algorithm based on color clustering to compress computer desktop image. It divides computer screen image into 16×16 non-overlapping blocks, then each block is classified into text/graphic block, hybrid block or picture block. For text/graphic blocks with rich color, a color clustering method is used to reduce the number of colors, then text/graphic block is coded by lossless compression. Natural image block is coded by H.264 intra prediction coding method. Hybrid block is coded by hybrid coding method. Experimental results show that the image by proposed algorithm has higher PSNR and SSIM than traditional algorithms.
  • LIU Chang-Yun, NI Lin
    Computer Engineering. 2012, 38(21): 226-228,240. https://doi.org/10.3969/j.issn.1000-3428.2012.21.060
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    Traditional Project onto Convex Set(POCS) algorithm for image super-resolution reconstruction has the defect of edge oscillation. Aiming at this problem, an improved POCS algorithm is proposed. By analyzing the reason that causes the edge artifact, for the greater pixel difference of the both sides of edge, it weighted restricts the Point Spread Function(PSF) whose center is the edge pixel, and reduces the influence of the other side of pixels to the current edge pixel. Experimental results show that this algorithm can reduce the edge oscillation effectively and improve the Peak Signal to Noise Ratio(PSNR) of the reconstructed image.
  • SU Pin-Gang, CHANG Li, CHEN Jie, YA Ting-Qin
    Computer Engineering. 2012, 38(21): 229-231,244. https://doi.org/10.3969/j.issn.1000-3428.2012.21.061
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    Aiming at the problem that the image generated by Millimeter Wave(MMW) focal plane imaging system is contaminated by much unknown noise and has lower resolution, a novel image denoising method, combined with Human Visual System(HVS) based self-adaptive median filtering and contourlet transformation, is proposed in this paper. The noise is self-adaptively detected and filtered by using the method of HVS-based adaptive median filtering, and pulse noise is filtered efficiently. Utilizing the contourlet decomposition orientation and the energy variation to transform the median filtering result, the high frequency sub-bands are obtained, and they are further denoised by the threshold, which retains more image contour in degree. Experimental results show that that the proposed method has better denoising performance than other methods.
  • FENG Xiao, XU Jin-Fu, DAI Zi-Ban, LI Wei
    Computer Engineering. 2012, 38(21): 232-236. https://doi.org/10.3969/j.issn.1000-3428.2012.21.062
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    Functional verification is the major bottleneck in Integrated Circuit(IC) design. Aiming at simulation generating and coverage model issues, this paper proposes an efficient method based on Classification Tree Method(CTM). This method successfully practices on functional verification of modular addition/subtraction cell. By introducing CTM to manage simulation vectors and to construct coverage model, the integrity and reliability are improved markedly.
  • ZHANG Wen-Dong, HUANG Chao, BO Yun-Yan
    Computer Engineering. 2012, 38(21): 237-240. https://doi.org/10.3969/j.issn.1000-3428.2012.21.063
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    String chart is an important map in the petroleum industry. To improve the working efficiency of field staff, the drawing system of string chart based on the technology of Flex is developed. Due to the issues of the low efficiency and standardization during the process of drawing string charts, the idea of design patterns is introduced, the general design scheme and drawing algorithm of the string chart drawing system are given, which has interactive function, and the data of well trajectory is preprocessed by minimum curvature method. Experimenal results show that the system is designed successfully, for its beautiful interface and strong interactive. It has a certain value to application and can be widely used in related units such as CNPC and Sinopec.
  • LIU Zong-Zhen, LEI Yuan-Yuan, CHEN Qiu-He
    Computer Engineering. 2012, 38(21): 241-244. https://doi.org/10.3969/j.issn.1000-3428.2012.21.064
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    Highways of Dedicated Short Range Communication(DSRC) protocol-based Electronic Toll Collection(ETC) system is expensive and has poor versatility. To solve these problems, it simplifies On-board Unit(OBU) error message frame processing, designs and implements communication frame’s analysis and packaging in data link layer and application layer using microcontroller, which is in line with the complex consumer transactions of ETC application process specifications. By porting program to OBU hardware system, test results show that the system is stable, and timeliness is in line with national standards.
  • WANG Shuai, HAN Jun, LI Yang, CENG Xiao-Xiang
    Computer Engineering. 2012, 38(21): 245-248. https://doi.org/10.3969/j.issn.1000-3428.2012.21.065
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    Security protocols and cryptography algorithms(ciphers) are widely used to protect the sensitive digital information in computer systems and communication networks. How to process these computation-intensive protocols and algorithms has become a crucial issue. This paper presents a Network on Chip(NoC) architecture for Wireless Local Area Network(WLAN) security domain. Four MIPS-like RISC processors and twelve security-oriented ASIPs fabricate the proposed 4×4 mesh NoC architecture. In each ASIP, the Parallel Look-Up Table (PLUT) method is implemented to accelerate Advanced Encryption Standard(AES) encryption. Moreover, task parallelism in Counter CBC-MAC Protocol(CCMP) is exploited, thus high throughput is obtained. The proposed architecture is synthesized under SMIC 0.13 μm CMOS technology and costs 3083 k-gates. Experimental results show that the system achieves a throughput of 787 Mb/s at 84 MHz.
  • JIANG Jian-Chun, LIU Chao
    Computer Engineering. 2012, 38(21): 249-252,256. https://doi.org/10.3969/j.issn.1000-3428.2012.21.066
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    Facing to Distributed Real-time Systems(DRS) of automotive electronic, communication middleware must handle many aperiodic and periodic communication events under strict time requirements, they can not control communication time. This paper proposes a communication middleware of distributed real-time application referencing AUTOSAR standard by requirements of real-time and flexible configuration mechanism. It has reusability, tailorability and configurability, can hide the difference of communication protocols and be used to different operation system and platforms. Application case analysis of a communication middleware show its feasibility.
  • HE Jun, ZHANG Xiao-Dong, GUO Yong
    Computer Engineering. 2012, 38(21): 253-256. https://doi.org/10.3969/j.issn.1000-3428.2012.21.067
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    Aiming at the problem of the inefficiency of the Translation Look-aside Buffer(TLB) of a homegrown microprocessor, based on the analysis of current virtual to real address mapping program, a method of TLB architecture optimization is put forward, which is to setup a separate virtual to real address mapping cache of the base address of third level page tables, decreasing the occurrence of replacement of higher level page table entries by lower level ones. After evaluation using SPEC CPU2000 benchmark, the Double Miss(DM) rate of the data TLB of almost half of the benchmarks is dropped down by 60% at least and some of the benchmarks are decreased by 90% above, such optimization can reduce data TLB miss rate effectively.
  • QIN Meng, LEI Gang, YAN Hai-Feng
    Computer Engineering. 2012, 38(21): 257-260. https://doi.org/10.3969/j.issn.1000-3428.2012.21.068
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    This paper focuses on the basic test method and test procedures in Serial RapidIO(SRIO) device interoperability test. With the test report from RIOLAB as an example, the test procedures, test targets and other related technical questions are specifically explained and analyzed. After introducing the software and hardware platforms, it discusses what is valuable for designers to build their own projects. With the help of all the analysis above, a simple test is taken to prove the feasibility of the test method, in order to support and prepare for constructing more complete test method.
  • DING Lin, ZHANG Si-Ying, LU Jiang-Chun
    Computer Engineering. 2012, 38(21): 261-263,267. https://doi.org/10.3969/j.issn.1000-3428.2012.21.069
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    In order to discuss cascading failures on complex networks subject to attacks or random failures, this paper proposes a betweenness-based one to explore the robustness of weighted scale-free networks against cascading failures. It is found through numerical simulations and theoretical analysis that the betweenness-based strategy has the optimal weighting parameter, which is almost the same as that of the degree-based strategy. With the optimal weighting parameter, the betweenness-based strategy makes the networks more robust, showing that the possibility of the occurrence of the cascade dynamics and the size of the cascade in case of occurrence is more significantly reduced.
  • WANG Hui, WANG Bin
    Computer Engineering. 2012, 38(21): 264-267. https://doi.org/10.3969/j.issn.1000-3428.2012.21.070
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    In the burst signal processing environment, the traditional test statistic of the computational complexity is not conducive to real-time detection. So this paper gives a burst signal detection algorithm based on the goodness of fit test by applying Kolmogorov test instead of parametric test methods. By calculating Kolmogorov statistics variable which is the maximum distances between the experience function of distribution and the standard function of noise distribution, and contrasting with the threshold on the specific probability of false alarm, it can achieve detecting for burst signals. Simulation results show that the algorithm can obtain better detection performance.
  • LIU Chi-Kang, ZHANG Jian-Hai, YAN Rong-Gang, YANG Qiong
    Computer Engineering. 2012, 38(21): 268-271. https://doi.org/10.3969/j.issn.1000-3428.2012.21.071
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    In order to address the problem of grid-based method that a big change in the surface of the model will cause inadaptability of the algorithm, an algorithm of automatic hexahedral mesh generation based on logical grid is proposed. The proposed algorithm improves grid-based method and avoids generating initial grid in one time, but disperses the model into a series of section. Initial grid is formed by using vector intersection method for adjacent section. By modifying initial grid, a layer of mesh is formed. Every layer of mesh is assembled to form total meshes. By using improved grid method, automatic mesh generation for blocks of arch dam abutment with complex topography is accomplished. The results show that the algorithm proposed can adapt complex topography better. The elements are degradation automatically when the surface of model has a big change.
  • WANG Fu-Li, OU Yang-Jian-Quan
    Computer Engineering. 2012, 38(21): 272-275. https://doi.org/10.3969/j.issn.1000-3428.2012.21.072
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    This paper proposes a fingerprint retrieval method of multi-feature fusion based on AdaBoost to improve the robust of video fingerprint. The proposed method can gain the weight of Scale Invariant Feature Transform(SIFT), temporal and audio feature adaptively by training the sample data, then fuse audio-video feature to produce video fingerprint according to the weights of the three features. Experimental results show that this method can gain higher accuracy, and have good robustness under various geometric, brightness modification and audio noise.
  • LI Cheng-Yu, YANG Xiao-Long, HAN Zhuang-Zhi, LI Zhi-Jiang, HE Jiang
    Computer Engineering. 2012, 38(21): 276-278,282. https://doi.org/10.3969/j.issn.1000-3428.2012.21.073
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    In order to improve the survival ability of radar, and keep the radar tracking ability at the same time, this paper proposes a target tracking technology of fire control radar based on adaptive pulse interval. An improved signal model and normal signal is proposed. Extended Kalman filtering algorithm for Constant Acceleration(CA) target is expounded. The principle of choosing pulse interval based on adaptive technique is introduced and interception possibility is analyzed. Simulation results show that this technology can achieve a high accuracy of target tracking and prolong signal intercept time, and reduce the interception probability of reconnaissance system for fire control radar.
  • SU Lian-Hua, GUO Yang, YANG Ji
    Computer Engineering. 2012, 38(21): 279-282. https://doi.org/10.3969/j.issn.1000-3428.2012.21.074
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    This paper proposes a new rate control algorithm for I frames in H.264/AVC based on rate, buffer status and complexity of sequences. Using edge information, two R-Q models for I frames are established in the forms of power and exponent. The number of target bits for the first I frame is corrected based on the pre-encoding of the first four frames. Experimental results show that the proposed algorithm can increase the average Peak Signal to Noise Ratio(PSNR) of reconstructed videos, depress the fluctuation of PSNR, and avoid frame skipping significantly.
  • YANG Di
    Computer Engineering. 2012, 38(21): 283-285,289. https://doi.org/10.3969/j.issn.1000-3428.2012.21.075
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    Ternary Content Addressable Memory(TCAM)-based packet classification methods suffer from the range expansion problem. In this paper, an efficient range encoding method to solve this problem is proposed. It divides all the unique ranges in each field of rules into different groups, and uses the shadow encoding method to re-encode them, rewrites the original rule set according to re-encoding ranges. Experimental results show that this method can reduce TCAM storage space by 75.90% on average.
  • LIU Dan-Zhu, YIN Shou-Yi, YAN Chong-Yong, LIU Lei-Bei, WEI Shao-Jun
    Computer Engineering. 2012, 38(21): 286-289. https://doi.org/10.3969/j.issn.1000-3428.2012.21.076
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    As reconfigurable processor hardware is inherently parallel, compiler should determine the best execution mode by analyzing the parallelism. So this paper proposes a parallel optimal algorithm based on reconfigurable processor. The parallel computing part of Direct Acyclic Graph(DAG) is mapped to reconfigurable processor. The task compiler can cover parallelism at three different levels: Instruction-Level Parallelism (ILP), Loop-Level Parallelism(LLP), and Thread-Level Parallelism(TLP). Test result shows that the algorithm leads to an average 1.2-fold speed increase compared with to original systems.
  • JIN Qian-Qian, LIN Dan
    Computer Engineering. 2012, 38(21): 290-292. https://doi.org/10.3969/j.issn.1000-3428.2012.21.077
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    For the problem that Undirected Capacitated Arc Routing Problem with Profits(UCARPP), a Variable Neighborhood Search(VNS) algorithm is proposed. Generating the sequence of the demand side, initializing each edge of the same probability in the direction, the initial solution is generated by the split algorithm, six kinds of neighborhood structures are designed to do the wide area search, local search is proposed to improve the solution, the rotary wheel algorithm is applied to select the neighborhood structure. Experimental results show that the algorithm can improve the efficiency, avoid the early convergence and have better stability.