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15 August 2013, Volume 39 Issue 8
    

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    Networks and Communications
  • YANG Yi, CHEN Guo-Shun, BAO Chang-Chun
    Computer Engineering. 2013, 39(8): 1-4. https://doi.org/10.3969/j.issn.1000-3428.2013.08.001
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    The purpose of the speaker classification system is to segment and classify speech data according to different speaker. It improves performance of the speaker classification system by extracting multi-delay feature based on multiple distance microphones. With the number of microphones increases, the multi-delay feature vector dimension grows rapidly. Aiming at this problem, a method is proposed with keeping manifold structure and reducing the computational cost. It uses the multi-component discriminant locality preserving projections algorithm based on multiple distance microphones acoustic merging feature. Experimental results show that Diarization Error Rate(DER) of this algorithm can be reduced to below 20% and is better than traditional methods in most of the data set.

  • LV Feng, JIANG Beng, TUN Qin-Zhang
    Computer Engineering. 2013, 39(8): 5-8. https://doi.org/10.3969/j.issn.1000-3428.2013.08.002
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    As T-tree has not good cache behaviors and update efficiency, this paper gives some optimization design for T-tree. The structure of T-tree’s node is redesigned according to the technology of cache structure and layout, and the precursor and successor pointers are added into the node structure. That can make T-tree more cache conscious and enhances its ability of range query. When there is a data overflow while updating, multiple data items rather than a data item are transferred between nodes. So the chance of data overflows and rebalancing trees can be reduced and the update performance is improved. Experimental results show that the improved T-tree has a better performance in query and updating and can save 18% main memory space.

  • JIAN Quan, GU Pan-Long, ZHANG Rui
    Computer Engineering. 2013, 39(8): 9-14. https://doi.org/10.3969/j.issn.1000-3428.2013.08.003
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    With the fast development of Radio Frequency Identification(RFID) and tag usage, security has become the key issue for RFID related applications. In this paper, a new RFID secure protocol is proposed, which uses a synchronized random number created in the backend system, for tag authentication. After tag successful authentication each time, both tag and random number update synchronously. Meanwhile, the performance and security of the protocol are analyzed theoretically. Also the BAN logic is used to prove its security in further. The result show that this protocol can provide authentication between tag and reader, moreover, it can resist attacks such as replay, location tracking, traffic analysis, counterfeiting, denial of service, and illegal access, etc. From the implementation point, it just uses Hash and exclusive XOR operations, which reduces the computing complexity and makes it fitting for low price tags applications.

  • GUO Meng-Jiang, HUANG Ying, XIE Zhong
    Computer Engineering. 2013, 39(8): 15-19. https://doi.org/10.3969/j.issn.1000-3428.2013.08.004
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    In order to improve the concurrent access performance of WebGIS system in a cluster environment, two level parallel processing mechanisms are proposed. One level is among each service node in the cluster and the other is within the service node. The calculation method of task response ratio, the request queue buffer mechanism and multi-thread scheduling strategy are focused on to improve system performance. Experimental results show that the WebGIS model can fully use the multi-core computing advantage of server nodes under the concurrent access environment. The more CPU core, the higher concurrent processing capabilities is enhanced.

  • LI Wei, ZHANG Shou-Meng, BI Gui-Gong, MENG Wei
    Computer Engineering. 2013, 39(8): 20-26. https://doi.org/10.3969/j.issn.1000-3428.2013.08.005
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    This paper researches on Hybrid Human Immunodeficiency Virus(HIV) transmission mechanism, and proposes a dynamic mixed scale-free network generation algorithm based on the configuration model for investigating HIV transmission. It takes homosexual transmission network and heterosexual transmission network into the same system according to transmission law between man and man, man and woman, and forms a homosexual and heterosexual mixed-propagation network. In order to reflect the real social network evolution process, this algorithm adds the dynamic nature of network. The configuration model is presented to support scale-free rapid flexible and robust generations of dynamic mixed scale-free networks with given size and power law degree distributions. The dynamics of network is supported through network links dissolution and reformation. This configuration model avoids the shortcomings of the classic BA model. Simulation results show that the algorithm can correctly and effectively reflect the characteristics of the mixed-propagation network.

  • QIN Ai-Na, DAI Liang, GUI Wei-Hua
    Computer Engineering. 2013, 39(8): 27-30,37. https://doi.org/10.3969/j.issn.1000-3428.2013.08.006
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    An improved speech enhancement algorithm is proposed by analysis the human auditory masking properties when a serious problems of residual musical noise brought by the Spectral subtraction in low Signal Noise Ratio(SNR). The gain parameters are adjusted by combined human auditory masking properties with wiener filter. Noise estimation is used by the Minimum Controlled Recursive Averaging(MCRA) algorithm in non-stationary environment. In order to further eliminate the musical noise, the optimal smoothing factor based on Minimum Mean Square Error(MMSE) is used to smooth the enhanced voice. Simulation results show that compared with the improved spectral subtraction and Wiener filtering method, the algorithm can effectively suppress background noise and residual musical noise as well as maintaining speech quality and intelligibility in low SNR.

  • CHEN Chun-Guang, ZHANG Kun-Long, TAN Long-Fei, HAN Zhao
    Computer Engineering. 2013, 39(8): 31-37. https://doi.org/10.3969/j.issn.1000-3428.2013.08.007
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    Self-organizing linked lists perform well for handling requests with strong locality. Non-blocking algorithm can provide better robust and reliable. It uses MTF(Move-to-Front) concurrent rule to do concurrent operation, and presents the non-blocking self-organizing linked list algorithm which supports linearizable search, insert and remove operations using CAS primitive. Experimental results show that this algorithm performs well for long linked lists with high percentages of search operations. With the data sequence in experiment, when the percentage of lookup reaches 90% and the data range becomes 4 096, it provides the best performance.

  • CANG Tong-Zheng, LV Ke-Wei
    Computer Engineering. 2013, 39(8): 38-43,54. https://doi.org/10.3969/j.issn.1000-3428.2013.08.008
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    The original Hidden Number Problem(HNP) usually works with a prime modules or a special form composite number modulus. To break through the limitation, this paper presents a method which can resolve the HNP in regular non-prime modulus case. It promotes the HNP in prime modulus case to the HNP in prime powers modulus case by introducing the Hensel-lifting method and lattice rounding technique in a creative way, and combines the Chinese remainder theorem to receive the achievement. Analysis result shows that the discrete logarithm computational problem under the Hensel-lifting situation can be reduced to the HNP in prime modulus case.

  • MA Bao-Qiang, SHANG Yi-Beng, YAN Hang-Chen
    Computer Engineering. 2013, 39(8): 44-49,59. https://doi.org/10.3969/j.issn.1000-3428.2013.08.009
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    Aiming at the problem of high algorithm complexity, low monitoring efficiency and privacy disclosure for existed monitoring system of elderly people living alone, this paper proposes a monitoring system for elderly people living alone based on omni-directional vision. It uses Omni-directional Vision Sensor(ODVS) to get panoramic image, and designs a Motion History or Energy Images(MHoEI) algorithm for the motion object tracking. In the posture recognition, different human model algorithms are applied in accordance with the imaging characteristics of ODVS. For the behavior analysis, a calibrated one-to-one correspondence is adopted between the ground locations and the environmental factors. Both the reliability of behavior detection and the robustness of behavior detection are significant expanded. In addition, elderly activities are accurately obtained by using ODVS calibration and effective tracking for the human object. Experimental results show that this system has high robustness, instantaneity and accuracy rate of the detection. It is adequate to meet current needs by protecting privacy.

  • XIONG Zheng-Li, JIANG Wen-Jun, WANG Guo-Jun
    Computer Engineering. 2013, 39(8): 50-54. https://doi.org/10.3969/j.issn.1000-3428.2013.08.010
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    Aiming at the problem that it is difficult to detect the potential community of Online Social Networks(OSNs), based on the unique characteristics of OSNs, this paper proposes the new concept of user tightness, and designs a community detection algorithm based on it. It creates the initial user graph, computes user individual tightness based on node attribute similarity algorithm, and computes user community tightness based on common neighbor similarity algorithm, to create the integrated user graph, it processes the integrated user graph with hierarchical clustering algorithm, to detect the potential communities. Experimental result shows that compared with NAS algorithm and CNS algorithm, the detected communities of this algorithm have much higher degree of cohesion and accuracy, and reach 0.67 and 97.1%.
  • CA Bei-Shi, CHEN Xiang
    Computer Engineering. 2013, 39(8): 55-59. https://doi.org/10.3969/j.issn.1000-3428.2013.08.011
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    To solve the problem of matrix sparseness of the weibo social network and the problem of limited meaning of the community detected based on social relationship. This paper proposes a weibo community detect model based on behavior similarity. By selecting related indexes from weibo and using Principal Component Analysis(PCA), it reduces the dimension of the indicators. It applies modified Clique Percolation Method(CPM) to discover community of weibo and dichotomizes the input matrix to reduce the computation of CPM algorithm. By collecting real data from Sina weibo, it compares new method and traditional method which builds model on connectivity attribute. The results show that this new method has higher clustering coefficient which is 5 times more than the traditional one, which shows that community discovered by new method has stronger cohesion.
  • MENG Jing, TUN Ti-Sheng
    Computer Engineering. 2013, 39(8): 60-63,68. https://doi.org/10.3969/j.issn.1000-3428.2013.08.012
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    The traditional Local Outlier Factor(LOF) algorithm need recalculate the local outlier factors of the all of data when does the second outlier mining in dynamic incremental database environment. This paper proposes an outlier mining algorithm based on clustering and rapid calculation. It improves the traditional DBSCAN algorithm, uses the improved DBSCAN algorithm to form a set of clusters, and computes the local outlier factors of the objects which are a part of dataset. Experimental results show that this algorithm performs better than LOF and lncLOF algorithm not only in the time consuming but also the accuracy of mining outliers.
  • BO Xun, DU Jia, LEI Xian-Liang
    Computer Engineering. 2013, 39(8): 64-68. https://doi.org/10.3969/j.issn.1000-3428.2013.08.013
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    This paper proposes an Improved Discrete Particle of Swarm Optimization(IDPSO) to optimize the task scheduling problem of cloud computing with user priority level preferences in a short time. It combines the user priority and the task deadline to establish an appropriate task priority to guide the algorithm fitness function, employs a re-optimization criterion to ensure that the algorithm has the ability to jump out of local optima, and ultimately obtains task scheduling mapping with user priority preference. Simulation experimental results show that this algorithm is fit for cloud computing environment, it can gain overall optimal task scheduling scheme.
  • ZHANG Lei, GAO Jiang, SHU Zhen-Min, XIE Jian
    Computer Engineering. 2013, 39(8): 69-73. https://doi.org/10.3969/j.issn.1000-3428.2013.08.014
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    The development of mobile computing technology makes people able to get online reading resources in a mobile environment. It is becoming a problem how to retrieve contents matching users’ interest from massive resources, therefore, a resources recommendation algorithm oriented mobile reading platform is proposed. The algorithm applies the feature of users’ knowledge structure and social intercommunication records into the calculation of similarity between users to get the nearest-neighbor set of the collaborative filtering method. Test result on the system platform shows that absolute error average value of the proposed algorithm is 0.636, it is lower than average level of recommendation system, the recommendation algorithm is effective.
  • SUN Ming-Ze, GUO Wei, ZHOU Gong-Ru, WEI Ji-Ceng
    Computer Engineering. 2013, 39(8): 74-76,82. https://doi.org/10.3969/j.issn.1000-3428.2013.08.015
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    For System on Chip(SoC) architecture design, the simulation speed of Register Transfer Level(RTL) modeling is slow, and system modeling using C language lacks of enough accuracy. To solve these problems, this paper presents a Cache Transaction Level Modeling(TLM) method with cycle-accurate and bits-accurate, using electronic system level design methodology. In the model, different abstraction layers are adopted in the external interfaces and internal logic. The SoC is constructed based on the Electronic System Level(ESL) design, and realizes the S/H co-design. Experimental results show that the simulation platform with the Cache model is significantly reduced in the number of cycles when running the corresponding program, and achieves the established accuracy requirements.
  • ZHANG Beng, LI Qing-Bao, CUI Chen
    Computer Engineering. 2013, 39(8): 77-82. https://doi.org/10.3969/j.issn.1000-3428.2013.08.016
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    To solve the problem in dynamic control flow reconstruction that not all program execution paths can be explored, an algorithm based on execution path driven is presented. The main idea of this algorithm is to run the binary program in a controllable instrument environment, and drives it to execute the program paths which can’t be explored under current input set by modifying the value of Program Counter(PC), so that Control Flow Graph(CFG) can be reconstructed. Based on this algorithm, a dynamic path drive control flow recovery system is designed and implemented. Experimental results illustrate that this algorithm is effective in exploring execution paths. Compared with traditional dynamic algorithm and Interactive Disassembler(IDA), the coverage of CFG reconstructed by this algorithm is higher.
  • WANG Ting, LAN Ju-Long, WU Jun-Ting
    Computer Engineering. 2013, 39(8): 83-86,91. https://doi.org/10.3969/j.issn.1000-3428.2013.08.017
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    To reduce genome complexity and improve large-scale circuit evolution efficiency in complex hardware system, a Hardware Element Component Construction method Masking Differences of Underlying Hardware(HECCMDUH) is proposed in this paper. Hardware Element Component Coding method based on Gene Expression Tree(HECCGET) and the Shortest Path(SP) algorithm of hardware element component are proposed based on HECCMDUH method. SP algorithm can solve the shortest connection among hardware element components. It provides a new theoretical reference for real-time hardware reconfiguration of network switching device.
  • LI Qian-Ru, TAO Wei
    Computer Engineering. 2013, 39(8): 87-91. https://doi.org/10.3969/j.issn.1000-3428.2013.08.018
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    There are two important issues in software defect prediction. It is difficult to collect a large amount of labeled training data to learn a good model. The data set is always imbalanced, since the software system contains much fewer defective modules than non-defective modules. In order to solve out these two problems, this paper proposes a novel semi-supervised learning approach named Balanced and Biased Support Vector Machine(B2SVM). The method exploits the abundant unlabeled samples to improve the prediction accuracy, as well as employs sampling technology to handle the class-imbalance problem during the Biased Support Vector Machine(BSVM) learning process. Experimental results on class-imbalance dataset show that this method can go on software defect prediction for class imbalance sample set.
  • CENG Yi, LIU Jing-Xiang, WANG Cui-Qin, HONG Hao
    Computer Engineering. 2013, 39(8): 92-96,102. https://doi.org/10.3969/j.issn.1000-3428.2013.08.019
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    As the Unified Modeling Language(UML) can not describe the system model accurately and single model can only describe the system information from one level, it makes the polymorphism test incomplete. Therefore, it puts forward a method of polymorphic path test clues generation with Object Constraint Language(OCL) constraints. By adding OCL constraints into class diagram, taking into account the influence on testing caused by polymorphism of the class diagram and combining with UML class diagram, state diagram, as well as collaboration diagram, it designs the Inter-messages Restricted Control Flow Graph(MRCFG) under the OCL constraint, which includes the information of polymorphism and state. The test clues is generated by employing MRCFG path coverage criteria. The prototyping tool based on the above mentioned theory is realized, and proves this method enhances the degree of testing automation, and generated polymorphic test scenarios is more complete.
  • FENG Jing, LIU Zi-Dun, CHEN Ye
    Computer Engineering. 2013, 39(8): 97-102. https://doi.org/10.3969/j.issn.1000-3428.2013.08.020
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    There are different Quality of Service(QoS) requirements for Wireless Sensor Network(WSN) in different applications including guaranteed hard QoS, differentiated soft QoS and so on. Oriented best-effort and real-time applications, an adaptive sensor network routing protocol to support differentiated services, Adaptive Sensor network Routing Protocol(ASRP), is presented, which synthesizes directed diffusion protocol and Low-Energy Adaptive Clustering Hierarchy(LEACH), sets up two types of routing grade. ASRP makes use of different routing metrics and introduces gateway node to support both routing policies single-path and multi-path for best-effort and real-time applications respectively. The gateway nodes can link two cluster head nodes to implement multiple hops forwarding from one cluster head to sink, which has good scalability. Simulation result shows that ASRP can provide the different QoS for two type applications and improve power efficiency of the whole networks.
  • DAI Hong-Wen, MA Li, CHEN Hai-Bin
    Computer Engineering. 2013, 39(8): 103-106,111. https://doi.org/10.3969/j.issn.1000-3428.2013.08.021
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    Aiming at the signal transmission mechanism and characteristic of Human Body Communication(HBC), a more practical HBC system model is proposed and Finite Difference Time Domain(FDTD) is adopted to explore from the aspect of interaction between electromagnetic field and human body. Simulation results show that in HBC, signal transmission along the arm surface possesses the features of surface wave. Electromagnetic field has different attenuation constants in the direction parallel and normal to human body surface. It is noted that 500 MHz~600 MHz is the best communication frequency band for the human body transmission in the 0~ 1 000 MHz frequency range. Good communication can be achieved when transceiver is somewhat apart from human body surface.
  • WANG Jian-Quan, HU Yun, LV Shao-Biao, QIU Yong
    Computer Engineering. 2013, 39(8): 107-111. https://doi.org/10.3969/j.issn.1000-3428.2013.08.022
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    A multi-hop interference graph model is proposed which takes wireless link as a diagram in this paper. And capacity optimization formulated as “maximum flow problem” is analyzed based on this graph. It presents three optimization mechanisms to improve network protocol, such as “load-balancing”, “routing algorithm”, “rate adaption”. Theoretical analysis and simulation results show that the error rate of the model can be controlled within 10%, effectively improve mesh network performance.
  • HUANG Yu-Qing, WANG Yang-Lun
    Computer Engineering. 2013, 39(8): 112-116,120. https://doi.org/10.3969/j.issn.1000-3428.2013.08.023
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    The Media Access Control(MAC) protocol which coordinates idle channel accessing service among cognitive radio users, is one of the key technologies in cognitive Ad-hoc network supporting Quality of Service(QoS). This paper is based on the algorithm of binary exponential backoff, proposes a MAC algorithm with multi-agent Q-learning that supports service differentiation, real-time transmission probability adjusting is introduced to optimum the accessing service of system. Markov chain model is established with transmit probability adjusting, and the relationship between packet transmit probability and protocol parameters are derived. The channel throughput model with service differentiation is given. The multi-agent Q-learning architecture based on MAC protocol parameter is realized. Experimental result shows that this algorithm can satisfy the QoS of high priority service, the throughput rate and delay are better than IEEE 802.11e EDCA mechanism.
  • MENG Qiang-Ping, ZHOU Xin-Li, TIAN Wei
    Computer Engineering. 2013, 39(8): 117-120. https://doi.org/10.3969/j.issn.1000-3428.2013.08.024
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    The channel coefficients of the last frame are used to equalize the data of current frame. The channel coefficients are supposed to be constant during a frame of data, hard decision information is passed from equalizer to decoder, in order to solve these problems, three improved algorithms based on Data Directed Equalization Algorithm(DDEA) are proposed. The channel coefficients used to equalize the data of current frame are close to the true parameters according to iteration in hard decision iteration DDEA. The channel coefficients at every sampling interval are different in variable channel coefficients DDEA. Soft decision information is delivered between channel estimator, equalizer and decoder. Simulation result shows that the performances of these three proposed algorithms reach 3.5dB, 2dB and 6dB, they are improved at different degree, compared with the current DDEA.
  • SHU Jin-Fang, NI Yo-De, WANG Kai, QIN Zhe
    Computer Engineering. 2013, 39(8): 121-125,130. https://doi.org/10.3969/j.issn.1000-3428.2013.08.025
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    With the increment of Global Navigation Satellite System(GNSS) constellation and the development of dual-frequency technology, conventional Receiver Autonomous Integrity Monitoring(RAIM) algorithm which is used in en-route flight, can’t fulfill the integrity requirements of LPV-200 approach. Advanced Receiver Autonomous Integrity Monitoring(ARAIM) gradually appears which is applied in approach. Aiming at LPV-200 approach, the algorithm of ARAIM availability prediction is researched based on the theoretical analysis of Vertical Protection Level(VPL), studies the ARAIM availability prediction algorithm, and designs ARAIM instantaneous availability prediction system. Simulation results show that this system can meet the requirements of LPV-200 approach to integrity, the coverage rate of ARAIM prediction algorithm is up to 100% in Chinese area when availability is set to 99.9%.
  • LI Mu-Dong, XIONG Wei, LIANG Jing
    Computer Engineering. 2013, 39(8): 126-130. https://doi.org/10.3969/j.issn.1000-3428.2013.08.026
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    Grid scan algorithm is a typical range-free localization algorithm in Wireless Sensor Network(WSN). This paper analyzes and simulates the important parameters including average network connectivity, beacon nodes number, communication radius and grid length, which have great impact on location error, localization rate and time. The simulation results show that neighbor beacon nodes number of unknown nodes is the main factor which impacts on localization precision and rate. Grid length can improve the location error and total nodes number is the main parameter which affects the localization time. On the other hand, there are the optimum values of parameters in the fixed monitoring area, which can improve localization precision and rate effectively.
  • WANG Li-Bin, CUI Chen
    Computer Engineering. 2013, 39(8): 131-134,138. https://doi.org/10.3969/j.issn.1000-3428.2013.08.027
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    The model of wideband array output in the presence of mutual coupling is constructed through studying the model of narrowband array output and the idea of frequency diversity. Based on this model, a preprocessing algorithm of wideband signal is proposed with instrumental sensors. After this preprocessing, mutual coupling effects do not need to be considered when calculating the focusing matrices. Consequently, the focusing calculation procedure is conducted and the Direction of Arrival(DOA) is estimated directly without knowing the mutual coupling coefficients. Simulations show that this algorithm not only reduce the computational complexity, and the angle estimation accuracy using the proposed preprocessing algorithm is extremely close to the result in condition of accurately knowing the mutual coupling coefficients when the Signal to Noise Ratio(SNR) is more than 10 dB.
  • DENG Sai-Yu, TUN Ying, ZHANG Chi
    Computer Engineering. 2013, 39(8): 135-138. https://doi.org/10.3969/j.issn.1000-3428.2013.08.028
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    This paper deeply analyzes the cyclic autocorrelation property of Single Carrier-Frequency Domain Equalization(SC-FDE) signals and discusses the relationship between the cyclic autocorrelation function and the length of the useful signals and cyclic prefix. With no prior information, an algorithm for parameters estimation of SC-FDE signals is proposed. According to the property that the cross section is symmetrical about zero and the relationship between the length of cyclic prefix and the spectral line, this paper restricts the search of spectral peak to a specified region and estimates the length and the symbol number of the cyclic prefix. Simulation result proves that the algorithm improves the estimation accuracy, and has a better estimation performance even in the low noise signal ratio.
  • LI Zi-Mu, BANG Chi-Fang, FU Yi-Qi
    Computer Engineering. 2013, 39(8): 139-141,146. https://doi.org/10.3969/j.issn.1000-3428.2013.08.029
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    As IPv6 protocol can not be deployed directly in most Wireless Local Area Network(WLAN), based on the campus WLAN of Tsinghua University, this paper describes two development ways: stateful IPv4/IPv6 double stack access and stateless IPv6 access. Best implementation way of IPv6 in WLAN is studied. Operation result shows that these two ways can both provide good service to WLAN clients. Experience is accumulated for IPv6 promotion and WLAN clients accessing next-generation Internet.
  • SUN Zhi-Shuai, XIE Zheng, CHEN Zhi
    Computer Engineering. 2013, 39(8): 142-146. https://doi.org/10.3969/j.issn.1000-3428.2013.08.030
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    For finding the number of alternative routings in the network, this paper presents a new question of disjoint path, that is how to find the largest number of disjoint paths which exist at the same time in the network. And aiming at selecting the optimal route, consider the problem of getting K(K is an integer and K>1) disjoint paths, whose total weights are least. In addition, find the relation between the disjoint paths and the network flow and prove it. Benefiting from the network flow, a simple algorithm is designed. The results of application show that, the algorithm’s complexity is small. The algorithm can be used to solve the problem of multi-path routing in network communication.
  • JIN Ling, BAI Guang-Wei, CHEN Hang, CAO Lei
    Computer Engineering. 2013, 39(8): 147-152. https://doi.org/10.3969/j.issn.1000-3428.2013.08.031
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    This paper proposes a Network Coding-aware 802.11 Distributed Coordination Function(NCA-DCF) channel access mechanism. A Proactive Acknowledgement(PACK) strategy with collision avoidance is introduced to deploy a coding-aware scheme for each node. Through opportunistic forwarding, NCA-DCF can enhance the reliability in a single transmission. It develops a Markov chain model to characterize the NCA-DCF mechanism, in consideration of the characteristics of wireless network coding. Analysis result shows that NCA-DCF can avoid collision and improve channel utilization rate, it achieves significant performance improvement.
  • ZHANG Chao, LIANG Song-Chao
    Computer Engineering. 2013, 39(8): 153-155. https://doi.org/10.3969/j.issn.1000-3428.2013.08.032
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    In order to improve the data transmission efficiency of wireless networks, reduce the number of retransmission, a new network coded retransmission method is proposed. The network coding technology is applied to retransmission process of wireless network, and according to the packet loss information of the network node, the sender retransmits combined packets with network coding. According to decoding rules, the network node recovers the lost data from the combined packets. Theoretical analysis and simulation experimental results show that the network retransmission method based on network coding can effectively reduce the number of retransmission, and improve the performance of wireless networks.
  • CHEN Yu-Lei, JI Xin-Sheng, HUANG Kai-Qi, JI Jiang, ZHOU Lei
    Computer Engineering. 2013, 39(8): 156-160,165. https://doi.org/10.3969/j.issn.1000-3428.2013.08.033
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    Most multiuser Orthogonal Frequency Division Multiplexing(OFDM) wireless communication system resource allocation schemes are poor in secure transmission. This paper presents a method of multiuser OFDM system resource allocation scheme restricted in physical layer security. It constructs a multiuser OFDM wiretap channel model from the perspective of information security theory. Based on this model, the scheme utilizes joint optimization of subcarrier and power allocation, via dual decomposition method to achieve the system security rate maximization optimization target in conditions to fulfill the needs of each user’s security QoS. Simulation results show that when the system selects 64 sub-carrier to serve 8 authorized users, the secrecy capacity of the proposed scheme can be increased by 2.071 bit/s/Hz than the traditional schemes at most, and security QoS requirements of authorized users can be met at the same time.
  • YANG Chao, HU Jian-Bin, CHEN Zhong
    Computer Engineering. 2013, 39(8): 161-165. https://doi.org/10.3969/j.issn.1000-3428.2013.08.034
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    This paper introduces a traceable privacy-preserving authentication protocol for Vehicular Ad-hoc Network(VANET) based on a single hop Proxy Re-signature(PRS) in the standard model. It achieves some good features: The TRC designates the RSU translating signatures computed by the OBU into one which validness can be verified by the TRC’s public key. Therefore, it is prevented that vehicles are traced by their signatures on the messages, and attacks are thwarted by using an endorsement mechanism based on signatures. Security analysis shows that the protocol can achieve good conditional privacy target of VANET. Performance analysis shows that the protocol can also provide an efficient way to relieve workload by less storage and communication cost compared to the other classic protocols.
  • HU Yong-Bei, ZHENG Ye-Yang, SHU Jun
    Computer Engineering. 2013, 39(8): 166-168. https://doi.org/10.3969/j.issn.1000-3428.2013.08.035
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    This paper proposes a new template attack method in order to improve the efficiency of Advanced Encryption Standard(AES) template attack. This method includes a new attack algorithm and an optimized schedule. This new attack algorithm can access to the whole 128 bit key of AES by establishing Hamming weight template on each nonlinear table and 128 times of template classifications and this optimized schedule includes the preprocessing and principal component analysis of the signal. Experimental results show that this method can improve the efficiency of template attack and also decrease the memory usage and computing.
  • ZHANG Xiu-Jun, TUN Zhi-Jiang, FANG Zheng
    Computer Engineering. 2013, 39(8): 169-172. https://doi.org/10.3969/j.issn.1000-3428.2013.08.036
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    There are some problems for digital image encryption algorithm of low dimensional chaotic system such as small key space and low safety. On the basis of three-dimensional Lorenz system, by adding a new variable w to construct a four-dimension differential equations and adding a nonlinear term campaign to increase the complexity of the system, this paper establishes a novel four-dimensional hyperchaotic system. And an image encryption algorithm based on this hyperchaotic system is proposed and implemented. The system’s hyperchaotic properties is verified by the Lyapunov exponents calculation and simulation result of the trajectory of the system. By analyzing the security performance of the algorithm, it finds that the algorithm is extremely sensitive to key, has good diffusivity, and it can resist all kinds of attacks effectively such as brute force attack and known-plaintext attack.
  • WANG Chao, CHEN Xing-Yuan
    Computer Engineering. 2013, 39(8): 173-176. https://doi.org/10.3969/j.issn.1000-3428.2013.08.037
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    To solve the problem of nonlicet indirectly access in the information system, this paper proposes a conspire-accesses risk control model based on information flow graph. It forms an information flow graph through recording history accesses, and defines the conspire-accesses. It defines the access control model based on states machine, to prevent the conspire-accesses by security theorems and rules, and proves the security of the rules. It analyses and verifies the model’s validity based on information entropy theory, and the result proves that the model can prevent conspire-accesses.
  • WANG Qian, LI Yan-Jun, LIU Hong
    Computer Engineering. 2013, 39(8): 177-180,186. https://doi.org/10.3969/j.issn.1000-3428.2013.08.038
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    In view of the l-diversity problem in data with multiple sensitive attributes and the high hide ratio that presents privacy preserving methods may cause, a sensitive Attributes Classification Based Grouping(ACBG) privacy preserving method is proposed. It classifies the sensitive attributes according to the diversity and importance of each sensitive attribute, and sets different diverse values for them and groups the data, so it can meet the l-diversity for each. Experimental results show that this approach can protect privacy of data and reduce the hide ratio and enforce the usability of the shared data.
  • LI Shao-Bei, DIAO Yi-Fu, DIAO Qun-Fei, YAN Wei-Wu
    Computer Engineering. 2013, 39(8): 181-186. https://doi.org/10.3969/j.issn.1000-3428.2013.08.039
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    This paper takes a view of human pose and action recognition to realize human-robot interaction. A part detector for each human body part is obtained by AdaBoost algorithm. With these detectors, several candidate regions for the corresponding body part are found. During the finding process, the position and orientation of parts are both considered. These candidate regions are evaluated by using several defined evaluation indexes in order to select an optimal one. Human pose recognition and action imitation are implemented by using a NAO robot as test bench, and NAO’s performance shows good spatial consistence and temporal consistence within its ability of operation. The result shows that the algorithm can effectively identify and imitate human posture.
  • ZHANG Xiang-Qun, ZHANG Xu
    Computer Engineering. 2013, 39(8): 187-189,195. https://doi.org/10.3969/j.issn.1000-3428.2013.08.040
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    A new subspace learning algorithm, which is called Two-dimensional Discriminant Locality Alignment(2DDLA) algorithm, is proposed for pattern classification, such as face recognition. The proposed algorithm integrates the idea of discriminant locality alignment and two-dimensional feature extraction algorithm. 2DDLA operates in the following two stages: First, in part optimization stage, for each sample, it constructs local patch by seeking for the nearest neighbors. An object function is designed to preserve local discriminant information. Second, in whole alignment, the alignment trick is used to align all part optimizations to the whole optimization. The projection matrix can be obtained by solving a standard eigen-decomposition problem. Experimental results on ORL face database show that the algorithm has better superiority and robustness.
  • ZHANG Jian-Meng, SUN Chun-Mei, YAN Ting
    Computer Engineering. 2013, 39(8): 190-195. https://doi.org/10.3969/j.issn.1000-3428.2013.08.041
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    In order to solve the problem which the rate of label accuracy sharp declined due to video shots of same concepts exhibit dissimilar visual features when they are from different domains, a semi-supervised active learning algorithm based on adaptive Support Vector Machine(SVM) for video annotation is proposed. This algorithm migrates the existing classifier into adaptive SVM classifier by the introduction of function Δ and the optimization of model parameters, and obtains the evaluation function by comprising a fusion of the semi-supervised learning based on Gaussian fields and harmonic functions and the active learning based on adaptive SVM, and labels videos through the evaluation function. Experimental results show that the Mean Average Precision(MAP) and Mean Average Recall(MAR) of the proposed algorithm are respectively 68.1%, 60% in cross-domain video concept detection, the results are significantly improved compared with Support Vector Machine Semi-supervised Active Learning(SVM-SAL) and Transducitve Support Vector Machine Semi- supervised Active Learning(TSVM-SAL).
  • WANG Jin-Yun, ZHOU Hui-Jie, JI Zheng
    Computer Engineering. 2013, 39(8): 196-199,203. https://doi.org/10.3969/j.issn.1000-3428.2013.08.042
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    This paper proposes a fast face detection and recognition algorithm based on face image in the complex background. The process includes complexion model and OpenCV integrated method to solve face detection and location, re-save image, pretreatment, and illumination influence will be conquered effectively, eliminates the disadvantage factor disturbance of complex background. Afterward, it adopts Two-dimensional Principle Component Analysis(2DPCA) algorithms to collect face image of different expression which comes from the same human and distill character, and classifies the similar face image. By ORL database and outfield face image test, experimental results show that this method resolves face location and recognition effectively in the complex background and has more fast and effective practicability than other means, over 90% correct recognition rate.
  • CHEN Xiao-Lou, DAI Meng, YIN Chuan-Li, JI Xiao-Jiang, WANG Zi-Chen
    Computer Engineering. 2013, 39(8): 200-203. https://doi.org/10.3969/j.issn.1000-3428.2013.08.043
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    To solve the problem of gray projection algorithm that the accuracy of electronic image stabilization will reduce when there is local movement in the video frame, this paper introduces the Dynamic Time Warping(DTW) technique into to the algorithm. Using the traditional gray projection algorithm to get images’ projection curves on row and column, and correcting them with DTW algorithm, this method can get optimal deformation paths both on row and column and analyze the distribution of the optimal matching points so as to get the global moving vector. Experimental results show that the correct matching rate of this method is above 95%, which reduces occurrence rate of wrong match and improves the accuracy of electronic image stabilization.
  • LI Zhi-Tong, YI Jun-Kai
    Computer Engineering. 2013, 39(8): 204-207,214. https://doi.org/10.3969/j.issn.1000-3428.2013.08.044
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    In general, the conventional word-form based Chinese text categorization approach which does not give further consideration on Chinese linguistic feature often has poor performance. A new algorithm of Chinese text categorization based on sense group is proposed. This algorithm extracts sense group by analyzing Chinese dependency parsing results and developing extraction rules. Here uses Support Vector Machine(SVM) to training test documents to build the category sense group library which is used in test. Experimental results display that the method based on sense group reaches accuracy up to 97%, which is 3% higher than the way which is based on words.
  • SUN Jing-Jie, DIAO Jian-Jun, YANG Li-Bin, SANG De-Yi, TAO Gang
    Computer Engineering. 2013, 39(8): 208-214. https://doi.org/10.3969/j.issn.1000-3428.2013.08.045
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    Aiming at problems such as low evolutionary efficiency and redundant immune network which are caused by the algorithm design for Artificial Immune Recognition System(AIRS), a new artificial immune classifying method is proposed. The implementation of this method include: positive selection and network suppression are applied with Monte Carlo method to generate optimal distributing initial antibodies according to training antigens. Immune response process is imitated by using many kinds of immune mechanisms to evolve mature memory cells from initial antibodies. Classification is accomplished by majority vote of the K nearest memory cells. The classifying results for UCI data set demonstrate that, compared with AIRS, the antibodies evolutionary iterations and the network compression ratio of the new method respectively reduces 63.1% and rises 14.7% on average. In the fault diagnosis experiment for a linear stabilized voltage supply, the average classification accuracy ratio of the new method is 92.5%, which higher than the result of AIRS and the neural network.
  • TUN Zhen-Guo, YANG Gong-Jiao
    Computer Engineering. 2013, 39(8): 215-218,222. https://doi.org/10.3969/j.issn.1000-3428.2013.08.046
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    Most traditional algorithms normalize the six parameters of an affine transformation, no fully affine invariant approach exists for the time being. Consequently, an affine invariant algorithm for image matching is proposed in this paper. This method simulates all image views obtained by varying the two camera axis orientation parameters. Then it covers the other four parameters by using Harris-Laplace detector and Scale Invariant Feature Transform(SIFT) descriptor. The new method allows to reliably identify features that have undergone significant affine transformations including large viewpoint and scale changes. This fact is substantiated by many experiments which present a comparative evaluation of different methods and results show that the new algorithm outperforms significantly the state-of-the-art methods SIFT, MSER, Harris-Affine, and Hessian-Affine algorithms.
  • TUN Jian, DAI Ji-Yang, YING Jin
    Computer Engineering. 2013, 39(8): 219-222. https://doi.org/10.3969/j.issn.1000-3428.2013.08.047
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    Aiming at the contradiction between rapidity and veracity during real-time route re-planning, a kind of mixed A* with hierarchical structure is presented. This method includes three levels, the global route planning, event triggered global re-planning and time triggered local route planning, which is realized respectively by the multi-layered A* method, local fast real-time A* method and multi-layer variable step A* long way. The result of numerical simulation under different threat shows that the method is able to realize the fast and accurate target of real-time air route re-planning.
  • XU Wen, WANG Bin
    Computer Engineering. 2013, 39(8): 223-226,230. https://doi.org/10.3969/j.issn.1000-3428.2013.08.048
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    This paper addresses the problem of automatic modulation classification of the existed digital signal, according to the method of artificial classification, a classification method based on Support Vector Machine(SVM) is developed. The characteristic parameter of high-order cumulants of the signal is used for training data and test data. Comparing with the method of SVM for modulation classification existed, this method adopts SVM based on mixture kernel function and makes use of two classification of decision tree’s way to design classification process. By comparing the simulation results, indicates that the mixture kernel function of the SVM has a better classification performance.
  • ZHANG Ran-Ran, LONG Hai-Bei, ZHANG Yi
    Computer Engineering. 2013, 39(8): 227-230. https://doi.org/10.3969/j.issn.1000-3428.2013.08.049
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    Traditional blotch detection algorithms obtain higher correct detection rates by reducing the value of threshold. However, the corresponding higher number of false alarms affects the following correction results directly. To maximize the ratio between correct detections and false alarms, this paper proposes an improved blotch detector based on simplified rank-ordered difference. The improved detector can achieve the most appropriate threshold to the different blotch in a certain frame by introducing dual-steps adaptive multi-threshold. It uses employment of texture matching to avoid the possible deviation caused by motion vector estimation in the regions with blotches. Performance evaluation is taken to the image sequences with both real blotches and artificially corrupted ones separately. Experimental results indicate higher correct detection rates and fewer false alarms simultaneously.
  • LIANG Chao, WANG Liang, LIU Gong-Yun
    Computer Engineering. 2013, 39(8): 231-234,238. https://doi.org/10.3969/j.issn.1000-3428.2013.08.050
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    Monocular Simultaneous Localization and Mapping(SLAM) is computational complexity, and it is hard to reach real-time process. In order to solve this problem, this paper proposes an SLAM optimization algorithm. It uses the Feature from Accelerated Segment Test(FAST) corner to extract the environment featrures, and makes the Binary Robust Independent Elementary Feature(BRIEF) descriptor for every feature points, and improves the execution efficiency of the algorithm. 1-point Random Sample Consensus(RANSAC) algorithm is introduced to improve the algorithm framework, to reduce the computational complexity of algorithm and to achieve real-time processing of visual SLAM. Experimental results show that when the camera speed is 30 frames per second, the proposed algorithm can meet the real-time requirements.
  • XU Wei, WANG Zheng-Qun, LI Feng, ZHOU Zhong-Xia
    Computer Engineering. 2013, 39(8): 235-238. https://doi.org/10.3969/j.issn.1000-3428.2013.08.051
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    In order to overcome the shortcoming that Locality Preserving Projection(LPP) algorithm does not use label information for face recognition and the extracted feature of LPP can not achieve good classification results, this paper proposes a LPP based on rejection graph and attraction graph algorithm. The algorithm rejection graph and attraction graph based on K-nearest-neighbor(KNN) graphs. Rejection graph reflects the relationship between two near-by samples which is in different classes and attraction graph reflects the relationship between two samples which is not near-by, but in the same class. It combines rejection graph and attraction graph to extract feature, defines the similarity of samples to remove the effects of noise and eigenvalues variation when extracting the original feature. Experiments on Feret and Yale face image datebase show that the recognition performance of the proposed algorithm is higher than Principal Component Analysis(PCA) algorithm and LPP algorithm.
  • SUN Shi-Bao, DUAN Jian-Hui
    Computer Engineering. 2013, 39(8): 239-242. https://doi.org/10.3969/j.issn.1000-3428.2013.08.052
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    Aiming at the problem of blur boundaries and low computational efficiency in traditional image interpolation algorithms, an image interpolation algorithm based on edge gradient is proposed. It uses Roberts edge detection operator to determine the color segmentation and interval boundary threshold, makes use of three space points to constructed plane, and gives the interpolation formula. Experimental results show that, this algorithm can protect the image details, improves image scaling quality and operation efficiency.
  • LUO Bin, GE Shuang-Quan
    Computer Engineering. 2013, 39(8): 243-248. https://doi.org/10.3969/j.issn.1000-3428.2013.08.053
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    Current assembly induction Augmented Reality(AR) system can not implement seamless induction between starting with assembly tasks and performing assembly operations when using traditional interaction methods such as mouse and keyboard. To solve this problem, Color Predicate(CP) based single finger gesture interaction method is proposed and combined with ARToolkit to develop block-stack assembly induction AR system. The primary application and analysis results show that this method has strong robustness indoors and is capable of seamlessly inducing users to accomplish part assembly task more rapidly in AR assembly applications.
  • LI Meng, CENG Jian-Chao, HE Xiao-Juan
    Computer Engineering. 2013, 39(8): 249-252. https://doi.org/10.3969/j.issn.1000-3428.2013.08.054
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    Bayesian statistical inference theory is added in the process of building the probability model of estimation of distribution algorithm. This paper proposes a discrete distribution estimation algorithm based on Bayesian statistical inference. A model of a priori probability is built according to the distributing regularity of the problem’s solution. The model of conditional probability is constructed through combining the probability model of advantage groups with forest structure of Bivariate Marginal Distribution Algorithm(BMDA). The model of posterior probability is given by combining the above mentioned probability model to guide new population generating. Simulation results show that the algorithm convergence rate is greater than the EDAs1 when solving the gr21 Traveling Salesman Problem(TSP). Analyzing the effect of combining speed and learning rate for this algorithm under the condition that parameters are fixed, such as population size and maximum running algebra etc. The results show when their values are 0.2, the algorithm performance is the most stable.
  • CHEN Xi-Xiong, LIANG Cuo-Meng, HUANG E-Fei
    Computer Engineering. 2013, 39(8): 253-256. https://doi.org/10.3969/j.issn.1000-3428.2013.08.055
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    To solve complex function optimization problems, by combining Quantum Particle Swarm Optimization(QPSO) algorithm with good-point set method, an Improved Chaos Quantum Particle Swarm Optimization(ICQPSO) algorithm is proposed. Good-point set inserts to QPSO algorithm, improves the solution space ergodicity, to achieve global optimization for a function. Tthrough a chaotic sequence change inertia weight(w), to adjust QPSO algorithm’s global and local optimization ability. By linear decline rate proportion contraction factors η improve search speed, to avoid premature convergence. Through quantum Hadamard gate to variation quantum code, enhance the diversity of population, and promp the particle jump out of local extreme value point. The typical complex functions’ simulation results show that the hybrid optimization algorithm has high efficiency, fast convergence speed, effectively avoid premature convergence, and the optimal performance is much better than other optimization methods.
  • LV Biao, BO Yun, LIU Hai-Xu
    Computer Engineering. 2013, 39(8): 257-261. https://doi.org/10.3969/j.issn.1000-3428.2013.08.056
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    In view of travelers’ risk aversive route choice behaviors under a stochastic road network, a second-best congestion pricing bi-level programming model considering both the reliability and the unreliability of travel time is proposed. In the upper level model, the optimization objective is to maximize the social welfare of the road network in the presence of congestion pricing, while the lower objective is an elastic demand mean-excess traffic equilibrium model. In consideration of the complexity of bi-level programming model, Genetic Algorithm(GA) is presented to solve the proposed model. Simulation results show that, it is feasible to solve the proposed model using GA, which can converge to the target value after 50 iterations.
  • LI Lan, SHI Fei-Long, XU Nan-Nan
    Computer Engineering. 2013, 39(8): 262-265. https://doi.org/10.3969/j.issn.1000-3428.2013.08.057
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    The face images are decomposed using multi-level wavelet transformation to get the Local Phase Quantization(LPQ) features. The membership grades of the test images to the training images under different level are fused based on the fuzzy theory. This paper proposes a face recognition method by fuzzy multi-scale LPQ. Doing experiments on the ORL and FERET face database, results show that this method can get high recognition rate, not only effectively extracts the face feature but also solves the problem of high-dimensional feature that the original multi-level method brings. It shows better robustness to non-uniform illumination and noise.
  • LAI He-Lang, CHEN Gong-Yang, LAI Bo-Xian, KE Mo-Tian
    Computer Engineering. 2013, 39(8): 266-269. https://doi.org/10.3969/j.issn.1000-3428.2013.08.058
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    Banks election using a heuristic algorithm has the problem that the efficiency is low in the implementation, so this paper proposes a solving method based on Answer Set Programming(ASP). It establishes the mapping from Banks election problem to the ASP problem, writes the corresponding ASP, calls the answer set solver to solve, and each ASP model obtained is a solution of the Banks election problem. Experimental results show that when the problem size is 200, the solving time of this method is 4.196 s, solving efficiency is better than that of manual heuristic method.
  • WANG Chang-Da, DAN Ting-Juan
    Computer Engineering. 2013, 39(8): 270-273,280. https://doi.org/10.3969/j.issn.1000-3428.2013.08.059
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    A method of intelligent learning based on the concept map and weight optimization is proposed. By the knowledge in teaching content abstract concept map, the use of test stack based on weight optimization exacts targeted test questions after students learning, and according to test results, personalize teaching content is displayed to the students in order to realize intelligent and personalized learning. Model analysis shows that, compared with traditional intelligent tutoring systems, intelligent learning based on concept map and weight optimization improves the efficiency of students learning.
  • SHI Pei-Bei, HU Yu-Juan
    Computer Engineering. 2013, 39(8): 274-276,284. https://doi.org/10.3969/j.issn.1000-3428.2013.08.060
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    Due to the existing pedestrian detection system can not meet the requirement of high detection rate, low false positive rate and fast detection, a pedestrian detection system based on fast cascade classification is proposed. This system consists of pretreatment and classification detection. In the classification detection phase, it selects parts of the optimal features by AdaBoost algorithm, fixes the false alarm rate of the training samples and designs a fast cascade classifier combining the advantage of the serial connected classifier. The single feature classifier uses the quick sort strategy to redesign which improves overall system performance. Simulation results show that the Area Under Receiver Operating Characteristic Curve(AUC), F-measure and G-mean results of the FastCascade are higher than traditional AdaBoost algorithm, UnderSampling algorithm and EasyEnsemble algorithm.
  • LI Xiao-Yin, YAN Lian-Shan, BO Wei, LUO Bin, GUO Zhen, GUO Qiang-Feng
    Computer Engineering. 2013, 39(8): 277-280. https://doi.org/10.3969/j.issn.1000-3428.2013.08.061
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    Aiming at Radio Frequency Identification(RFID) localization problem for indoor environments, an UHF RFID tag localization method based on power scanning of reader is proposed. A path loss model is proposed to study the power of reader as a function of read range. The function is analyzed based on an empirical model that often used in indoor environments and Friis transmission equation in theory, and demonstrated in experiments. Based on the function, a circle localization using multiple RFID antennas is proposed. Experiment demonstration using two antennas shows that the average accuracy value is 57 cm. The factors that affect the location accuracy are studied, and then an improved localization method is proposed. Statistical results indicate that the average accuracy is improved from 57 cm to 18 cm using three antennas, and the location accuracy in terms of 90% probability within 25 cm. Meanwhile, decreasing the step of the power adjustment can also improve the location accuracy.
  • LIU Hua-Beng, CHEN Yi-Chang, DIAO Chang-Long, HE Li-Yun
    Computer Engineering. 2013, 39(8): 281-284. https://doi.org/10.3969/j.issn.1000-3428.2013.08.062
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    According to the characteristics of Ball Grid Array(BGA) chip mounted technology, analyzing the characteristics of chip solder balls arranged, a technology of BGA chip detection centring based on machine vision technology is proposed in this paper. Including the gray value histogram processing, dynamic threshold segmentation, system designs detection technology in VC platform combined with machine vision software, and it verifies the feasibility of this technology. Experimental results show that this technology improves the accuracy of the chip detection, guarantees the calculation speed, and is able to deal with nonlinear illumination.
  • NIU Chao, CHEN Hai-Bin
    Computer Engineering. 2013, 39(8): 285-287,291. https://doi.org/10.3969/j.issn.1000-3428.2013.08.063
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    A low cost design for elementary function approximation based on piecewise quadratic interpolation to support single- precision floating-point data, that can be able to complete the approximation to the reciprocal, squarer root, squarer root reciprocal, exponential, trigonometric and other elementary functions is presented. The traditional computation of quadratic polynomial needs one squarer, two multiplications and three additions. But this design only needs two Multiply And Accumulate(MAC) operations by the deformation of quadratic polynomial, and can complete the computation by reusing the MAC architecture. In the result, the design can reduce 56% of the computing area and save 17.5% cost of hardware in total, though the entire approximation operation takes two clock cycles to complete.
  • DIAO Chao, LIANG Jia-Gong, LI Meng
    Computer Engineering. 2013, 39(8): 288-291. https://doi.org/10.3969/j.issn.1000-3428.2013.08.064
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    In this paper, according to the real-time generation problem of walking engine of virtual human, based on the motion capture data, the Principal Component Analysis(PCA) method is introduced into the research on generic walking engine of virtual human, and realize real-time walking engine. Interpolation and extrapolation are achieved in the PCA spaces of each subject to generate new motion according to a speed value. A time warping method allows handling the human height parameter. Experimental result shows that the walking engine based on PCA method can produce smooth walking motions with real-time reactivity.
  • CHEN Zhuan-Gong, HU Xu-Fu
    Computer Engineering. 2013, 39(8): 292-294,298. https://doi.org/10.3969/j.issn.1000-3428.2013.08.065
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    The blind pursuit of low processor execution frequency does not necessarily get an effective energy saving effect in Dynamic Voltage Scaling(DVS) energy saving implementation of real-time system. The energy consumption of real-time task is not only related to the power, but also related to its execution time, to reduce voltage/frequency results in the increasing of execution time thus induces the increasing of energy consumption. In this paper, through static analysis of energy consumption model based on DVS in data center of real-time system, a new approach to determine the optimal initial execution frequency for processor to complete transactions is proposed. Instance data calculation results show that based on the optimal initial frequency to complete the transaction can save about 30% of energy consumption than just using the maximum processor frequency.
  • LIN Yi, GONG E-Li
    Computer Engineering. 2013, 39(8): 295-298. https://doi.org/10.3969/j.issn.1000-3428.2013.08.066
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    To optimize B-spline curve, this paper researches the influence of the length of the boundary tangent vector of B-spline parametric curves, and gives an iterative search algorithm which uses the binary search method to search the best boundary tangent vector length. At each step, it uses the binary search method to calculate the length, uses the curvature ratio to assess the search result, and feedbacks the results to determine the next search direction. Experimental results show that the B-spline curve optimized by this algorithm can describe the image edge properly, and the algorithm has a faster speed and robustness.
  • TUN Yang, JIANG Dong-Xin, FU Xiao-Long, LIU Qi-Xin
    Computer Engineering. 2013, 39(8): 299-302. https://doi.org/10.3969/j.issn.1000-3428.2013.08.067
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    According to the trend of the development of Knowledge Management(KM), this paper proposes a new dimension model-based Knowledge Management System(KMS). By researching the general characteristics of knowledge, it puts forward a knowledge model based on knowledge dimension, discusses knowledge organization mode and management method based on the dimension model, and designs a KMS based on the dimension model. In this system, knowledge service and search engines based on the dimension model are introduced to deal with the knowledge dimension and its relevant information. Experimental results show that the management system fuses dimension model, it has personalized features, strong interactivity and user sensitivity.
  • DUAN Mei-Jun, JIN Wei-Dong, YANG Zhi-Xin
    Computer Engineering. 2013, 39(8): 303-306. https://doi.org/10.3969/j.issn.1000-3428.2013.08.068
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    To make up for the sorting and recognition ability of the traditional five-parameter for Radar Emitter Signal(RES), this paper presents the evaluation method of RES intra-pulse characteristics based on fuzzy matter-element analysis. It designs evaluation indexes from time complexity of the feature extraction algorithm and space complexity of characteristics, gets objective weights of indexes by projection pursuit model based upon accelerating genetic algorithm with real coding, and uses the fuzzy matter-element analysis to evaluate the complexity of RES’s intra-pulse characteristics and does the simulation for six typical RESs. Experimental results show that this method is objective, effective, and can evaluate the complexity of RES’s intra-pulse characteristics more roundly and accurately.
  • WANG Rong-Yang, JIAN Zhen-Hua, YAN Yong-Hui
    Computer Engineering. 2013, 39(8): 307-313. https://doi.org/10.3969/j.issn.1000-3428.2013.08.069
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    Ultrasonic crosstalk, which can seriously result in false distance measurement and lessen the work efficiency of ultrasonic distance measurement system, often occurs when multiple transducers work together. Using the cross-correlation characteristic of pseudo-random sequence technique can eliminate the phenomenon of ultrasonic crosstalk by calculating the cross-correlation function of a detected ultrasonic wave and a transmitted ultrasonic wave. A parallel digital correlation algorithm is proposed by using xor and add operation instead of multiplication. The results of Programmable Logic Gate Array(FPGA) simulation demonstrate that the proposed method can eliminate ultrasonic crosstalk and errs, and shorten algorithm computation, the processing time and improve the utilization ratio of FPGA resource, the precision of distance measurement system.
  • LU Yong-Wei, WANG Xiang-Jun, ZHANG Ning-Ning, GU Gui-Min
    Computer Engineering. 2013, 39(8): 314-317. https://doi.org/10.3969/j.issn.1000-3428.2013.08.070
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    In order to meet the demands of centralized processing and evaluation of training data from multi target-scoring systems under a background of large-scale military training in digital range, a multi-grade remote control and information synchronous acquisition and processing as well as display method is proposed based on integration of Multi-carrier Wireless information Local Loop(McWiLL) and RS-485 networks. A multithreaded remote control and data exchange technology are proposed based on TCP/IP in the wireless environment of McWiLL, the upper computer can be conveniently operated by training appraisers because of its friendly human-computer interaction and data management based on document/view structure, a multi-machine monitoring and control network is designed based on RS-485, a two-level judgement of the synchronous head and upper computer number are adopted in order to realize the data exchange between the monitoring computer and many upper computers. The requirements of remote monitoring and automatic evaluation as well as centralized display are met in this system.
  • CAO Xiao-Chu, CHANG Shao-Yang, JIN Di, WANG Zong-Ren, WANG Qi-Di
    Computer Engineering. 2013, 39(8): 318-321. https://doi.org/10.3969/j.issn.1000-3428.2013.08.071
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    A method of 3D visualization based on Bézier curve is presented according to process and interpretation in seismic data. Keeping data sample density and imaging efficiency in a certain range by interpolating and fitting with quadratic Bézier curve or sampling seismic data. Based on the signal variable character, seismic data is mapped to corresponding vector color domain with cubic Bézier curve. Two ways for parameter quantification are given during transformation. Experimental results show that interpolation based image has obvious stereoscopical and geological character.