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15 April 2015, Volume 41 Issue 4
    

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  • LIU Haiyan,LIU Yun
    Computer Engineering. 2015, 41(4): 1-6. https://doi.org/10.3969/j.issn.1000-3428.2015.04.001
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    Network data fusion and cluster are effective technologies to reduce energy consumption of Wireless Sensor Network(WSN),however,clustering produces extra delays in the process of data aggregation,and the problem can be solved by the modified network structure. A Delay-aware Network Structure for WSNs with Data Fusion(DANSDF)is proposed. The proposed structure organizes sensor nodes into clusters of different sizes,each cluster can communicate with the fusion center in an interleaved manner. Simulation results show that compared with Low Energy Adaptive Clustering Hierarchy(LEACH),Delay-aware Data Collection Network Structure(DADCNS) the two network structures,DANSDF can reduce the delay in the process of data fusion,and can keep a low energy consumption.

  • LIU Shuying
    Computer Engineering. 2015, 41(4): 7-13. https://doi.org/10.3969/j.issn.1000-3428.2015.04.002
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    Target localization and tracking technology is currently a hot issue in Wireless Sensor Network(WSN). Conventional target tracking algorithms always require an explicit system observation model of the target positions, which,however,would fail if such model is not available. This paper designs a distributed algorithm for the localization and pursuit of multiple mobile targets using mobile robot. By the proposed algorithm,all robots are categorized into two groups:the leaders,responsible for the target pursuit,and the followers,responsible for the formation and connectivity maintenance,and then the relation between convergence error and system parameter setting is analyzed theoretically. Simulation results show that the proposed target pursuit algorithm is proved to be able to achieve a controllable convergence error to the local maximum points,which depends on the moving speed and sampling rate of agents.

  • TAN Li,CHEN Yucheng
    Computer Engineering. 2015, 41(4): 14-18,25. https://doi.org/10.3969/j.issn.1000-3428.2015.04.003
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    In the existing directional sensor networks,the centroid point of node model mostly rotates around the sector vertex. As in this model,the node rotation area is a full circle,and therefore multiplies the network energy consumption and deployment time. For coverage optimization problem of Wireless Sensor Network(WSN) in complex area,this paper uses the new directional model which the sector nodes rotate around the centroid in the previous work,then presents a coverage optimizing algorithm in complex area based on virtual potential field (COACA) to implement deployment optimization by reducing the node’s rotation area. Finally,it makes simulation for this algorithm to explore the parameters which will affect the coverage ratio and contrast with PFPCE algorithm. The simulation results show the high performance of the COACA algorithm in both coverage radio and time efficiency.

  • LI Na,XIANG Fenghong,MAO Jianlin,DAI Ning,DUAN Shaomi
    Computer Engineering. 2015, 41(4): 19-25. https://doi.org/10.3969/j.issn.1000-3428.2015.04.004
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    Aiming at the presence that obstacles exist in the monitored area,introducing a kind of obstacle avoidance strategy,this paper puts forward a PCMOD(Potential field based Coverage optimization algorithm to multi-obstacle scene for directional sensor networks). The algorithm is based on the directional sensing model,by means of overlapping coverage area,the effective coverage and virtual force of interaction between obstacles block area,adjusts node sensing direction and gradually eliminates the network of overlapping coverage and blind area, and improves the boundary condition by adding a neighbor node in the boundary line,makes sensor network coverage enhancement. On this basis,it analyzes the impact of sensor parameters on coverage rate. Simulation results show that the proposed algorithm can improve coverage rate in obstacle situation.

  • DONG Haitang,WAN Guofeng,LUO Yanhong
    Computer Engineering. 2015, 41(4): 26-29,35. https://doi.org/10.3969/j.issn.1000-3428.2015.04.005
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    Traditional area location algorithms based on midnormal have low positioning accuracy and number of iterations. Aiming at these problems,an Improved Midnormal-based area Localization Algorithm(IMBLA) is proposed in this paper. According to the value ratio of Received Signal Strength Indicator ( RSSI ) of two anchor nodes which unknown node receives,it moves two midnormals of the anchor,to determine the position relationship between a node and the midnormal. The algorithm does the RSSI raging using Gaussian correction model based on the reference anchor node, and puts forward the model in the presence of obstacles,which not only is suitable for a variety of environment,but also can effectively prevent malicious attacks. The simulation results show that,compared with MBLA and IPAIT algorithm, the IMBLA algorithm has higher positioning accuracy and coverage rate.

  • LI Jing,YIN Jian,LIU Shaopeng,PAN Yali
    Computer Engineering. 2015, 41(4): 30-35. https://doi.org/10.3969/j.issn.1000-3428.2015.04.006
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    With the development of the Internet,microblog has become a major platform for people to obtain the information. In order to mine useful topic from microblog,based on the futures of microblog that having conversation tags,retweet tags and hashtags,this paper divides microblog into three kinds. They are microblogs about users’ interest, users interaction and hashtag-related. It designs a novel hashtag topic model named Hashtag Conversation Author Topic Model(HC-ATM) based on Author Topic Model(ATM),and uses Gibbs sampling implementation for inference of this model. Experiments on Twitter dataset show that HC-ATM outperforms the ATM and MicroBlog Latent Dirichlet Allocation(MB-LDA) in terms of both perplexity and KL-divergence. Besides,HC-ATM can mine topic distribution of different kinds of microblog effectively.
  • GAO Mengchao,HU Qingbao,CHENG Yaodong,ZHOU Xu,LI Haibo,DU Ran
    Computer Engineering. 2015, 41(4): 36-40. https://doi.org/10.3969/j.issn.1000-3428.2015.04.007
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    Social network data has the features of informative and strong topicality with significant value for data mining,and it is also a very important part of the Internet big data. However,traditional search engines can not use the keywords retrieve technology to index the information of social network platform directly,and under such circumstances, this paper designs and implements a data collection model based on crowdsourcing mode and C / S architecture. The model consists of four modules including server,client,storage sub-system and a Deep Web crawler system. The nodes run the topic Deep Web crawler system to request new tasks automatically and upload the acquired data,meanwhile the system uses the Hadoop Distributed File System(HDFS) to process data rapidly and store results. The topic Deep Web crawler system has the features of easyconfiguration,flexible scalability and direct data collection,and it also proves that data collection model is able to fulfill the tasks in a high success rate and collect data in an efficient way.
  • JIN Weilin,CHEN Guoshun
    Computer Engineering. 2015, 41(4): 41-47. https://doi.org/10.3969/j.issn.1000-3428.2015.04.008
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    Explosion in big data has led to a surge in extremely large scale big data analytics platforms,resulting in burgeoning energy costs. In order to ensure the thermal-reliability of the servers,this paper proposes a data-centric technology for reducing cooling energy costs. It considers the uneven thermal-profile of the servers,the differences in their thermal-reliability-driven load thresholds,and differences in the data-semantics of the big data placed in the cluster. Based on this knowledge,the proposed technology does proactive,thermal-aware file placement,which ensures to reduce cooling energy costs and ensures thermal-reliability in the big data analytics cluster without any performance impact. Evaluation results with one-month long real-world big data analytics production traces from Yahoo Experimental results show that the technology reaches 42% reduction in the cooling energy costs and 9x better performance than the state-of-the-art dataagnostic cooling techniques.
  • ZHANG Jin,LIU Yan,LUO Junyong,DONG Yuchen
    Computer Engineering. 2015, 41(4): 48-54,59. https://doi.org/201504009
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    In recent years,there are some hype accounts in microblogs,they use illegal means to carry out the network public relations activities,which seriously disturbs the normal order of the Internet. The traditional detection of hype accounts mainly use methods based on manual analysis,which is inefficient and not suitable for detection of massive accounts. In view of the above problems,a method based on feature analysis for the detection of hype accounts is proposed. The features of hype accounts are analyzed from many angles,and a features database is constructed in this method,then the hype accounts are automatic classification by using several classification algorithms in data mining, including Naive Bayes(NB),Support Vector Machine(SVM) and K Nearest Neighbor(KNN),et al. Experimental result shows that this method is suitable for the detection of most hype accounts,with the accuracy rate of 95% .
  • ZHOU Shimin,CHAI Yunpeng,WANG Liang,WANG Xin
    Computer Engineering. 2015, 41(4): 55-59. https://doi.org/10.3969/j.issn.1000-3428.2015.04.010
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    Flash-based Solid State Drive ( SSD ) can improve the performance of On-line Transaction Processing (OLTP) database efficiently. Due to the high cost of SSD products,however,SSD is usually utilized in hybrid storage combined with traditional disks. Therefore,this paper proposes an adaptive data layout optimization algorithm and two specific strategies. The algorithm can adjust the characteristic of application adaptively,through observing and deciding the performance improvement efficiency of each data element,to form an optimized data layout between SSD and disks. Experimental results based on a practical database system show that the algorithm is flexible and efficient to adapt to various SSD capacity configurations,and can improve the performance of the OLTP database based on hybrid storage effectively.

  • YUAN Ming
    Computer Engineering. 2015, 41(4): 60-64,76. https://doi.org/10.3969/j.issn.1000-3428.2015.04.011
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    This paper proposes a method of building stock market network based on measuring weighted multi-fractal similarity among CSI 300 index stocks through multi-scale curve. It also studies the topology properties of the network. It tries to employ several classic algorithms,such as Fast Newman,Girvan-Newman,Louvain to find its community structure and determine the optimal threshold according to maximum modularity. This paper adopts portfolio MV model to further verify the method’s effectiveness. Experimental results show that the network based on multi-scale curve has scale-free, small world and rich club properties. This network has the best classification when using different community mining algorithms and displays robustness to these algorithms. The portfolio based on the community structure can reduce risk considerably.
  • CHENG Qianqian,WANG Lulu,ZHENG Tao,JI Donghong
    Computer Engineering. 2015, 41(4): 65-69,80. https://doi.org/10.3969/j.issn.1000-3428.2015.04.012
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    Existing microblog friend recommendation algorithms just use relatively simple information about user to make recommendation, they can not take full advantages of the rich user information and describes the profound characteristics of the user, and the result which in recommendation effect is not very satisfactory. Aiming at these problems,this paper presents an algorithm that uses the user’s tag,user’s content,the interaction between users and the user’s social topological information. It mines and computes topic relevancy,interest relevancy,intimacy score from these information and then uses K Nearest Neighbor(KNN) classification algorithm to recommend. Through experiments on Sina microblog user data set,and the results show that the algorithm can achieve better recommendation effect than content-based algorithm and social filtering-based algorithm,and the highest accuracy,recall,F1 measure respectively reach 16. 5% ,26. 8% ,19. 2% .
  • ZHAO Jihong,ZHANG Fang,QU Hua,DAI Huijun
    Computer Engineering. 2015, 41(4): 70-76. https://doi.org/10.3969/j.issn.1000-3428.2015.04.013
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    In order to fulfill the various Quality of Service(QoS) requirements of new services on the next generation Internet,this paper proposes a novel overlay QoS routing algorithm,which is named Penalty Factors-Multiple Constraint Pruning(PF-MCP) algorithm. The idea of pruning is applied by PF-MCP to handle multiple QoS constraint,such as bandwidth,delay and jitter. In order to select the optimal solution, penalty factor is introduced by PF-MCP to comprehensively evaluate the effective paths. Simulation experimental results by using fixed and random network layer topology shows that PF-MCP algorithm has higher QoS satisfaction rate,service node computation capability equilibrium and time complexity compared with Synthesize Priority Weight Routing(SPWR) algorithm,it has characteristics of small amount of routing calculation,strong network recovery capability and the optimal path selecting is credible. In summary,PFMCP can effectively fulfill its overlay QoS routing.
  • HU Feng,ZHENG Ziwei,JIN Tao
    Computer Engineering. 2015, 41(4): 77-80. https://doi.org/10.3969/j.issn.1000-3428.2015.04.014
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    Cooperative spectrum sensing can partly eliminate the multi-path and shadow effect. At present, most researches on cooperative spectrum sensing assume that Cognitive User(CU) is in static state,they do not consider that the CU mobility may make effect on the performance of cooperative spectrum sensing. In this paper,this factor about mobility of CU is considered and a model of dynamic cooperative spectrum sensing is put forward based on the centralized spectrum sensing. It makes that Primary User (PU) is static and some other CU move in a straight line at different speed in the model. Simulation and analysis result show that the dynamic CU can not cooperate with the static CU well on spectrum sensing by using lineal fusing rule along with the CU speed up gradually,so it can choose the CU at lower speed as the cooperative CU to increase the probability of detection.
  • YU Zidan,YU Huiqun
    Computer Engineering. 2015, 41(4): 81-86,91. https://doi.org/10.3969/j.issn.1000-3428.2015.04.015
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    In the research area of community detection in social network,there exists problem that some fast algorithms for large scale network are resulting in low quality community results,and lacking of model and mechanism to express user link attributes,some algorithms for with comparatively satisfactory detection result having high time complexity. This paper proposes a community detection algorithm for massive-scale social networks using MapReduce. This paper uses a new recommend trust model,which is evolved from PGP(Pretty Good Privacy),to compute the trust degree between users iteratively. More importantly, it proposes a community propagation model to assign nodes into communities. Finally,it conducts experiments with some typical network datasets and Sina microblog datasets,which shows the model this paper proposed can availably compute the trust degree between users,and a better result of community detection is gained.
  • XU Xiaoxiao,XIE Linbo,PENG Li
    Computer Engineering. 2015, 41(4): 87-91. https://doi.org/10.3969/j.issn.1000-3428.2015.04.016
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    Aiming at the problem that it is unable to get a more accurate location information indoors by using GPS positioning,this paper designs a positioning system using characteristics of WiFi signal strength based on Android platform,meets the demands of location information of indoor environment for people. The system consists of Android client,Tomcat server and MySQL database. Based on the general location fingerprint algorithm,this system adds MAC addresses to Access Point(AP) filtering,and gets the location fingerprint information by selecting fixed reference AP. On positioning stage,the weighting factor is added on the basis of the K-Nearest Neighbor(KNN) algorithm to further reduce the positioning error. Experimental results show that the system has the advantages of high precision and fast positioning, and it can achieve a good effect of indoor positioning.
  • LI Ya,TIAN Xinji
    Computer Engineering. 2015, 41(4): 92-95,101. https://doi.org/10.3969/j.issn.1000-3428.2015.04.017
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    An improved space-time coding transmission scheme is proposed in X channel with two antennas at each user. Each user employs full-rate full-diversity space-time block code. Part elements of each codeword are rotated by a certain angle and each codeword is pre-coded twice. One-level pre-coding aligns the unwanted codewords at each receiver. The unwanted codewords for each receiver are eliminated by the introduction of zero vector at each codeword and the linear operation at the receivers. The wanted codewords keeps orthogonal by the other pre-coding,thus the multi-user interference is cancelled. The transmission efficiency is improved compared with the existing space-time coding transmission for the same scene. Simulation results show that,with the same transmission rate,the transmission efficiency of the proposed scheme it can improve transmission efficiency,and has high reliability in same transmission rate.
  • LUO Yiping,ZHOU Bifeng
    Computer Engineering. 2015, 41(4): 96-101. https://doi.org/10.3969/j.issn.1000-3428.2015.04.018
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    The system which has complex network characteristic is widespread in natural and human society,considering the time-delay phenomenon during the information transmission,the problem of guaranteed cost for a complex network with delay is investigated. Designing a dynamic feedback controller and constructing a guaranteed cost control function,based on Lyapunov-krasovskii stability theory,combined with convex optimization of matrix inequality,a sufficient condition for the xistence of the guaranteed cost controller with time delay in complex network systems is obtained,and the least upper bound for the quadratic cost function method is gained. The dynamic feedback controller is designed to ensure the asymptotic stability conditions of the system and it makes the perfor mance index of the system meet certain requirements. For the system is given the upper bound of the guaranteed cost,the design of controller parameters can be obtained on the condition of the theorem. Finally,a numerical example is given to demonstrate the feasibility of proposed method.
  • LIN Jing,YE Fan,REN Junyan
    Computer Engineering. 2015, 41(4): 102-106,111. https://doi.org/10.3969/j.issn.1000-3428.2015.04.019
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    In order to solve the problem of non-ideal factors ( including Carrier Frequency Offset ( CFO ), I / Q imbalance,etc. ) introduced from analog front-end in bandwidth Orthogonal Frequency Division Multiplexing(OFDM) system,an effective CFO estimation scheme in frequency domain is proposed. Based on ECMA-368 standard,the signal model is built. Processing three consecutive preambles in the frequency domain,cosine function algorithm and tangent function algorithm can be adopted to estimate CFO. Simulation results verify that,compared with the traditional schemes, the proposed scheme is robust to big CFO and I / Q imbalance,thus it can provide better performance and enhance the robustness of the system.
  • SU Fanjun,NIU Yongmei,SHAO Qing
    Computer Engineering. 2015, 41(4): 107-111. https://doi.org/10.3969/j.issn.1000-3428.2015.04.020
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    In Data Center Network(DCN),Transmission Control Protocol(TCP) Incast occurs frequently when multiple servers send data to the same receiving end in parallel. Data traffic overflows the buffer at the bottleneck switch,leading to packet losses and subsequently TCP retransmissions. To solve TCP Incast problem,this paper presents TCP with fast feedback in DCN(FFDTCP). The congestion control algorithm of FFDTCP is based on Explicit Congestion Notification (ECN) and uses two bits to indicate four levels of congestion degree,then senders adjust congestion window according to the congestion information to achieve the purpose of reducing congestion and avoiding bottleneck link packet loss,leads to a sharp decline in throughput problem. NS2 simulation result shows that the algorithm can guarantee lower latency and higher throughput,effectively mitigate the TCP Incast problem and improve the transmission performance of DCN.
  • XU Libin,SONG Yuqing,LIU Yi
    Computer Engineering. 2015, 41(4): 112-116. https://doi.org/10.3969/j.issn.1000-3428.2015.04.021
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    Empirical Mode Decomposition(EMD) is widespread used in complex signal processing,but it exists the end effect in decomposition processing,and the end effect will further deepen with the process of filtration. Thus,it will cause data error. The methods of mirror extension and window function are effective methods for dealing with the end effect,but they are flawed. This paper presents a lifting method combining mirror extension and cosine window function. It makes up the deficiencies of mirror extension in original signal endpoint being not extreme value point and window function method in the need to change the original signal. Experimental result manifests that this lifting method can better restrain the end effect compared with some traditional methods.
  • LIU Ji, TAN Yuyin, FU Fa, Thomas Dreibholz, ZHOU Xing, BAI Yong, YANG Xiong, DU Wencai
    Computer Engineering. 2015, 41(4): 117-124. https://doi.org/10.3969/j.issn.1000-3428.2015.04.022
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    Multi-path TCP(MPTCP) and Concurrent Multipath Transfer for SCTP(CMT-SCTP) are two technologies of the concurrent multi-path transfer for NGI,which are hot topics. Compared with the traditional TCP and SCTP,the congestion control of multi-path transport protocols will face the problem of unfairness. This paper begins with an overview of the traditional TCP congestion control algorithm,and then in view of the unfairness of concurrent multi-path transfer,basing on the resource pooling method,it introduces the slow start threshold ratio factor,increase factor,per-flow aggressiveness factor,deduces three new algorithms to solve the problem of unfairness,and carryies out the contrastive analysis through simulation.
  • LI Weikun,YAO Xinwei,WANG Wanliang,WU Tengchao
    Computer Engineering. 2015, 41(4): 125-128. https://doi.org/10.3969/j.issn.1000-3428.2015.04.023
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    With the development of nanotechnology and the graphene-based nano materials,terahertz communication, the preferred communication technology of nano network is becoming the new hotspot for wireless communication. However,the performance of Multiple Input Multiple Output(MIMO) channel in terahertz band is still unknown. A novel MIMO channel model in terahertz communications is proposed by using a discrete mathematical method. Combining the molecular absorption and the path loss in terahertz band,a model of channel capacity is presented based on the channel state information at the receiver. MIMO channel model in terahertz communications is verified in the simulation. Result shows that the MIMO channel in terahertz communication can support higher capacity and transmission bit-rates than the single terahertz channel.
  • ZHANG Jing,LI Yan
    Computer Engineering. 2015, 41(4): 129-134. https://doi.org/10.3969/j.issn.1000-3428.2015.04.024
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    Now the network security evaluation method based on attack graph becomes the main research point,but most of the network attack models are analyzed from the standpoint of the attack side,and ignore the whole process of the connection relationship between offensive and defensive and the roughness of the knowledge system. This paper uses the rough access components association graph to describe the rough access relationship among the network components at some time and some special network topology state,through the rough characterization of the attack and defense policy set in the knowledge domain space to reflect the dynamic decision-making mechanism in the process of offensive and defensive. It gives the optimal attack policy-selection algorithm simultaneously,points out the most possible defensive policy in the current state of the network connection and the knowledge level of both sides of offensive and defensive. Examples show that the results of the analysis can help the defense side of the network administrator take related defensive measures better.
  • CHEN Yuan,MA Lin,ZHENG Min,YU Kai
    Computer Engineering. 2015, 41(4): 135-139. https://doi.org/10.3969/j.issn.1000-3428.2015.04.025
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    Specific to reliability and security problems in Mobile Ad Hoc Network(MANET),a trust evaluation model based on Dempster-Shafer(D-S) evidence theory is proposed. Direct trust degree is calculated with historical interaction information and indirect trust is obtained from neighbor nodes’ commendations. The direct trust degree and indirect trust are combined according to Dempster combination rule after being amended with weight,to obtain node’s comprehensive trust finally. On this basis,it optimizes the Multi-point Relaying (MPR) technology in Optimized Link State Routing Protocol(OLSR),and proposes an improved routing protocol (TOLSR). Simulation result shows that the model can discoveries selfish nodes and malicious nodes,thus effectively improves the reliability of MANET,which also proves the validity and rationality of the trust evaluation model.
  • TANG Changlong,LIU Jiqiang
    Computer Engineering. 2015, 41(4): 140-144. https://doi.org/10.3969/j.issn.1000-3428.2015.04.026
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    Data Allocation Strategy(DAS) system shows its advantages to address data leakage problems. This paper further illustrates the recent advances in DAS-based data leakage detection techniques including the first and second generation detection methods. Guilt model is demonstrated the potential as a suitable candidate for data leakage detection problems. The algorithms on explicit data request,random object allocation and agent selection are analyzed and evaluated with supporting data. Amodification on data allocation design is proposed. The experiment shows that the proposed algorithvs increases the possibility of detecting the guilt agents which leak the data. Consequently,the future works for guilt model are discussed.
  • HUANG Yila,XIONG Yan,LU Qiwei
    Computer Engineering. 2015, 41(4): 145-150,155. https://doi.org/10.3969/j.issn.1000-3428.2015.04.027
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    Unattended Wireless Sensor Network(UWSN) are usually deployed in a bad or hostile environment. The deployment of static aggregation node ( or base station ) is difficult, resulting in real-time information aggregation impossible. Hence the node should undertake the mission of self-sustaining the data temporarily. In order to improve the probability of data survival,on the basis of a clear assumption of the adversary model,this paper proposes a reliable data survival scheme with the failure node hypothesis,using the Chinese Remainder Theorem(CRT) based threshold secret share mechanism. The malicious nodes recovery attack detection mechanism is proposed based on the property of recovery inconsistency. Furthermore,the identification scheme towards malicious attack based on majority voting mechanism is also designed. Therefore,it can ensure the robust data survival well.
  • PENG Kaifeng,ZHANG Xi
    Computer Engineering. 2015, 41(4): 151-155. https://doi.org/10.3969/j.issn.1000-3428.2015.04.028
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    In the existing CP-ABE schemes that supporting attribute indirect revocation,the cost of revocation and its security can not be taken into account in the model simultaneously. Based on the idea of attribute indirect revocation and the dual system encryption technique,this paper constructs an adaptively security CP-ABE scheme that supports attribute revocation,and proves the security of the scheme using the 3P-SDP. Analysis result shows that,compared with the ABE schemes proposed before,the proposed scheme is more flexible and efficient in the access policy and attribute revocation.
  • BI Dongxu,LIN Jiajun
    Computer Engineering. 2015, 41(4): 156-160,165. https://doi.org/10.3969/j.issn.1000-3428.2015.04.029
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    Research on Complex Information Systems(CIS)is a big difficulty on a system of risk management and risk assessment because of the complexity of the structure. Based on Enterprise Architecture(EA)Zachman framework and GB / T 20984-2007 standard information security risk assessment norms, this paper presents a complex model of information system risk assessment framework and establishes a risk assessment process CIS. Based on risk management hierarchy and principle of security domain,it decomposes the architecture of CIS and studies assessment within and between domains. On the basis of traditional risk factors,the paper increases interconnection risk factor as the specific factor to the CIS,it introduces correlation to characterize interconnection and AHP method. With examples of CIS risk assessment process is validated,results show that the process can make an objective and accurate assessment for CIS risk.
  • CHEN Xiaolin,JI Bo,YE Yangdong
    Computer Engineering. 2015, 41(4): 161-165. https://doi.org/10.3969/j.issn.1000-3428.2015.04.030
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    Nonparametric Information theoretic Clustering (NIC) utilizes a non-parametric estimation of the average cluster entropies to maximize the estimated mutual information between data points and clusters,which effectively reduces the cost of participation. However,the algorithm assumes that all features of the sample to be analyzed plays a uniform contribution in the process of cluster analysis. Obviously,the hypothesis is inconsistent with a lot of practices. Therefore, this paper proposes a novel non-parametric feature weighting clustering algorithm based on ReliefF,which is named RNIC, to consider of different feature. It adopts ReliefF to transform and weighting features,R-NIC can inhibit redundant features,improves the clustering results by clustering in the transformed feature space. Experimental results on UCI datasets show that the performance of the proposed R-NIC algorithm is superior to the NIC algorithm.
  • Saimaiti Maimaitimin,HOU Min,Tuergen Yibulayin
    Computer Engineering. 2015, 41(4): 166-170. https://doi.org/10.3969/j.issn.1000-3428.2015.04.031
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    The step-by-step sentence alignment method is introduced in order to improve current Chinese-Uyghur sentence alignment method. Lexical and length information is used to generate some anchor sentences. Texts are divided into several sections by using anchor sentence as boundary,and then sentences in each section are aligned using lengthbased method. This method is effective in multi domain text because it uses words,numbers,and punctuation marks. It avoids complex computing and error spreading because of its “subsection” technique. Experimental results show that the precision of this method is 95. 2% in Chinese-Uyghur multi-domain texts,which is 2. 7% higher than length-based method.
  • HUANG Ting,JI Donghong
    Computer Engineering. 2015, 41(4): 171-175. https://doi.org/10.3969/j.issn.1000-3428.2015.04.032
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    For the further research of the function of emotional words on emotional analysis and the improvement of microblog emotional analysis method,this paper proposes a research approach to construct emotional words graph model using relations between emotional words. The emotional value of appraisal calculated by PageRank algorithm and trained as the feature of conditional random field model so as to forecast the tendency of emotional words in specific situations, through which subjectivity classification and emotional tendency analysis of microblog can be made when integrated with Support Vector Machine(SVM) model. Experimental results show that emotional lexicon constructed by graph model enhances accuracy of the prediction of emotional word in specific situations which is also helpful for subjectivity classification and emotional tendency analysis of mircroblog.
  • XIAN Xiaodong,SHI Yami,TANG Yunjian,YUAN Yupeng,FAN Yuxing
    Computer Engineering. 2015, 41(4): 176-180,186. https://doi.org/10.3969/j.issn.1000-3428.2015.04.033
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    In view of the instability and inaccuracy of bus passenger statistic with monocular vision based method,a new statistic method based on passengers’ multi-movement behavior is proposed,which combines the complexity and variety of passengers’ behavior. Passengers’ movement behavior is analyzed with trajectory clustering algorithm. The trajectory distance which is clustered with hierarchical clustering method is calculated according to the spatial feature and the directional feature of the trajectory. The clustering result corresponds to a certain kind of movement behavior of passenger,the influence of each movement behavior to the common counting criterion is discussed. In a result,the method based on passengers’ multi-movement behavior for bus passenger statistic is proposed. Experimental results based on the video when passengers getting on and getting off show that the method can obtain a high statistical precision and good stability.
  • LI Kui,FAN Yugang,WU Jiande
    Computer Engineering. 2015, 41(4): 181-186. https://doi.org/10.3969/j.issn.1000-3428.201504034
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    The number of feature values can be limited by using Singular Value Decomposition(SVD),which affects the accuracy of fault identification. A fault intelligent diagnosis method based on quadratic SVD and Variable Predictive Model-based Class Discriminate(VPMCD) is put forward,which can adaptively choose effective singular values firstly by using the curvature spectrum of singular values for reconstructing a signal. The same number of orthogonal components is acquired by SVD again,and the feature vector can be constructed by calculating its energy moment. The model of fault identification can be established by analyzing the feature vectors of using the VPMCD. This method is applied to the bearing fault diagnosis. Experimental results show that,in the normal and fault condition of bearing,the comprehensive identification precision of this method is 97. 5% ,and is 8. 75% higher than the conventional method based on SVD and Support Vector Machine(SVM).
  • NIAN Mei,ZHANG Lanfang
    Computer Engineering. 2015, 41(4): 187-189,194. https://doi.org/10.3969/j.issn.1000-3428.2015.04.035
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    In order to improve the performance of Uighur network content query expansion,this paper presents a kind of expansion words construction algorithm that is based on the combination of the Uygur synonym resources and Internet resources. An initial candidate words set is created by the Uyghur synonym,near-synonym and antonyms dictionary. The Internet is acted as a very large scale corpus,the similarity between the keywords and every word in the initial candidate words set is computed by the improved point mutual information algorithm. The words are sorted by the similarity evaluation and the top N words are selected to the candidate expansion words set-1. Meanwhile based on the partial collinear and point mutual information algorithm,it analyzes the Internet corpus which contained keywords and create the candidate expansion words set-2. The final expansion words are selected according to the results of weighted summation for the candidate expansion words set-1 and set-2. Compared with the normal keywords query and synonym expansion query,the query results based on the expansion words in this paper show that the accuracy of this algorithm is much better than the others.
  • FU Di,YIN Dong,SUN Tao
    Computer Engineering. 2015, 41(4): 190-194. https://doi.org/10.3969/j.issn.1000-3428.2015.04.036
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    Aiming at empty target and ambient noise,a background modeling algorithm is proposed. The image to be processed is filtered by three Gaussian blur filters in order to extract information stratified. Then,each layer builds splitting mixture Gaussian model group and computes change area. During processing, low-frequency information extracted from the upper layer is added to the modeling and gets contours of moving target which will join to the calculation of lower layer. The result tested on public video dataset indicates that the method ensures the accuracy of the extracted moving target when environmental noise is removed clearly. The method reduces the algorithm sensitivity for the scene illumination change and has a higher detection rate and lower false detection rate.
  • SHEN Songyan,CHEN Ying
    Computer Engineering. 2015, 41(4): 195-198. https://doi.org/10.3969/j.issn.1000-3428.2015.04.037
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    For non-rigid target contour tracking in a complicated environment has tracking failure problems,this paper proposes a snake model and its contour tracking algorithm based on online learning. The algorithm utilizes the Tracking-Learning-Detection(TLD) mechanism to achieve the goal of fast tracking,and updates snake model constraints through the tracking results to improve the accuracy of the target contour tracking. In the phase of initialization,the target to be tracking is divided into several blocks on the basis of GrabCut algorithm,and the algorithm realizes the sub-targets locating and tracking by the use of TLD in the subsequent tracking process,which forms the confident map of target outline. At the same time,the algorithm produces positive and negative samples and updates each target tracking model for each target feature extraction. The constraint of parameterized snake model is built through confident map and the contour of target is obtained. Experimental results show that the algorithm can adapt to the changing light and dark,and even more complex tracking environment,and obtains precise contour.
  • YUAN Zihua,LI Feng,ZHOU Shuren
    Computer Engineering. 2015, 41(4): 199-204. https://doi.org/10.3969/j.issn.1000-3428.2015.04.038
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    Tree structured model based on body parts is widely used in human pose estimation filed due to its intuitive expression and effective calculation. In order to address the problem of low accuracy of pose estimation caused by insufficient feature expression of body part models,a pose estimation method based on pictorial structure and novel text feature is proposed. Better appearance model is adopted,prior and latent relationships of different body parts are learned from annotated images then help in estimating better appearance models on test images. Haar characteristics Local Binary Pattern(HLBP) text feature is used to extract the text information of body parts. Furthermore,an image is block processed and different weight is assigned to different block. Experimental results show that when compared with HLBP,normed HLBP and color feature,Weighted HLBP(WHLBP) captures text feature more effectively and gains higher accuracy.
  • ZHANG Yaya,LIU Xiaowei,LIU Futai,ZHANG Jianting
    Computer Engineering. 2015, 41(4): 205-209. https://doi.org/10.3969/j.issn.1000-3428.2015.04.039
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    In view of Simple Linear Iterative Clustering(SLIC) method sometimes does not well adhere to the edge,this paper proposes an improved SLIC method to solve this problem. In order to reduce the influence of texture and noise information to images boundary location,the nonlinear diffusion filtering algorithm is introduced to smooth the images while preserving the boundaries and decreasing the noises. After the first iteration by using the principles of the Sigma filter, it increases clustering condition,improves the result of SLIC superpixels clustering,and enhances the accuracy of clustering center while reducing the inaccurate segmentation in the process of iteration. Simulation results show that the superpixels segmentation results of the proposed method have better performance in image details,and this method also increases the boundary hit rate without significantly increasing the processing time compared with the conventional SLIC method.
  • GUO Xiancao,SHI Meihong,LI Qing
    Computer Engineering. 2015, 41(4): 210-216. https://doi.org/10.3969/j.issn.1000-3428.2015.04.040
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    Aiming at the shortage of the discriminative ability to texture patterns for image texture classification using Weber Local Descriptor(WLD),an improved WLD based on Positive and Negative Gradient Features(WLD-PNG) is proposed. Positive and negative gradients are characterized by computing positive and negative differential excitations for preserving signed grayscale change information,and local texture structure information is represented by uniform Local Binary Patterns(uLBP). Combine both of them to build the image texture feature. The comparing experiments on the Brodatz and KTH-TIPS2-a texture databases demonstrate that WLD-PNG improves the distinctiveness of texture patterns, and has better robustness and lower computational complexity compared with original WLD,uLBP,WLD + uLBP and other improved WLD methods,etc.
  • LIU Wenjin,ZHANG Lei,SUN Jinguang
    Computer Engineering. 2015, 41(4): 217-221. https://doi.org/10.3969/j.issn.1000-3428.2015.04.041
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    When applying in the image stitching,some improved Harris corner detection methods still have defaults like only detecting corners in a single scale,the lost of corner detection information,unaccurate angular position and low detection rate caused by the sensitivity to noise. Combining bilateral filtering and multi-scale testing,this paper proposes an improved Harris corner detection method. The method uses a bilateral filter instead of the original Gaussian low-pass filter to enhance the robustness. The introduction of affinity propagation clustering method to block image avoids the uneven distribution of the corner caused by the threshold problems. The introduction of multi-scale concept to the improved method determines whether a candidate corner is true corner and excludes false corners,and makes corner detection more precise. Experiments are achieved in the platform of VS2010 + OpenCV. Experimental results show that, compared with the effect of the current corner detection method,the improved Harris corner detection method proposed in this paper can detect the image corners more accurately,achieves better effect and is more practical.
  • LIU Yan,ZHANG Jing,LV Min
    Computer Engineering. 2015, 41(4): 222-227,231. https://doi.org/10.3969/j.issn.1000-3428.2015.04.042
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    The existing massive crowd animation simulation methods have the defects of low quality and low efficiency in simulation. In order to solve these two problems,this paper proposes a method of combining storyboard with texture synthesis algorithms which can efficiently generate large scale crowd animation. Crowd’s positions,standing directions, status and information from the first frame including characters ’ path information from the subsequent frames are extracted and stored in the sample storyboard. And combining with block-based texture synthesis method,this sample storyboard can be used to enlarge the size of crowd efficiently. The final large-scale crowd animation can be simulated by using the enlarged storyboard in combination of simple collision detection algorithms. Experimental results prove the high efficiency and quality of this method in generating realistic large-scale virtual crowd animation.
  • TU Hong,GENG Guohua
    Computer Engineering. 2015, 41(4): 228-231. https://doi.org/10.3969/j.issn.1000-3428.2015.04.043
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    Differential coordinate is a powerful tool to characterize the geometry details of the grid model. Surface normal vector is a simple calculation,and it is not affected by noise as a first-order differential coordinates which can reflect detailed features of the grid model. This paper proposes an improved mesh smoothing denoising algorithm. The surface normal vector is transformed to the frequency domain using spectral mesh processing method through the Laplacian matrix decomposition. It can get smoothing facet continuous signal by low pass filter. The grid model is built through triangle barycenter constraints. Experimental results show that the algorithm is not easily affected by the noise, more robust than the vertex normal vector,and it can overcome the problems of volume shrinkage in the process of smoothing.
  • LIU Jing,GUO Jian,HE Zunliang
    Computer Engineering. 2015, 41(4): 232-235,240. https://doi.org/10.3969/j.issn.1000-3428.2015.04.044
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    In view of complex computation caused by extracting high dimension characteristics with local Gist method, as well as the problem that the sole Gist characteristic can not describe global scenes well,a kind of improved method to describe the scenes is proposed,which combines local Gist characteristics with Histograms of Oriented Gradient(HOG) characteristics. Classification accuracy of the sole characteristics and the combination of characteristics are inspected in the WS scene database using Support Vector Machine(SVM) as the classifier. On this basis,classified precision influenced by different quantity training samples is also studied in the OT scenes database. Experimental results show that this method reduces the computational complexity,and improves the classified accuracy compared with the global Gist,local Gist methods,etc.
  • JIANG Xiaoliang,LI Bailin,LIU Jiajia,WANG Qiang
    Computer Engineering. 2015, 41(4): 236-240. https://doi.org/10.3969/j.issn.1000-3428.2015.04.045
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    In order to overcome the problem of weak boundary and intensity inhomogeneity,a region-based active contour model for image segmentation is proposed in this paper. Using the global and local image information as the energy term driving evolution of active contour to the objective boundaries can effectively segment images with intensity inhomogeneity. In order to segment the image fast and accurately,the length term and penalty are incorporated into the energy equation. By adopting gradient descent method, the minimization of the energy equation can be given. Segmentation tests demonstrate that the proposed method can segment images with intensity inhomogeneity,needs less iteration and few iteration times,and is less sensitive to the location and size of the initial contour when is compared with the Local Binary Fitting(LBF) model and the Local Image Fitting(LIF) model.
  • LI Shaobo,WANG Xiaodong,ZHOU Yu,CHEN Meizi,ZHANG Lianjun
    Computer Engineering. 2015, 41(4): 241-245. https://doi.org/10.3969/j.issn.1000-3428.2015.04.046
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    For the data of stereo video is much larger and the current network’ s bandwidth cannot be upgraded immediately,it is easy to cause the network congestion problem in transmission. An end-to-end transmission control mechanism is proposed. In NS-2 platform,according to the feedback information,the number of packet loss is calculated in the feedback internal of RTP / RTCP and the characteristics of different frames with different importance,an active packet loss method at the sending is adopted to discard the less important data and to ensure the more important data transmit in advance. Experimental results show that the method can effectively protect important frames and increase frames which can be decoded and the smoothness of the video. Compared with congestion control of without the protection,the decoded frames can be increased by more than 25% .
  • LIN Xinqi,LI Haitao,LIN Yunmei
    Computer Engineering. 2015, 41(4): 246-252. https://doi.org/10.3969/j.issn.1000-3428.2015.04.047
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    Aiming at the time tampering problem in the single video shot,a new algorithm based on the content similarity is proposed to detect the tampers of frame duplication,deletion and insertion. Firstly,the three-scale visual contents are obtained by using the Gaussian pyramid transform on every frame. Then,the normalized mutual information is defined on the single scale visual content of adjacent frames based on information theory. And the descriptor of multiscale normalized mutual information is computed by linear combination. Thirdly,the abnormal degree of content similarity is computed by local outlier detection algorithm. Finally,the forgery places are detected by threshold. Experimental results show that the proposed algorithm can effectively localize the tamped position of the frame duplication,insertion,deletion tampers,and can be fit for the forgery of different coding formats and different cameras. The results also show that the proposed algorithm outperforms the existed algorithms in terms of precision and recall.
  • BI Guotang,TANG Quanhua,CHEN Liwei
    Computer Engineering. 2015, 41(4): 253-256,262. https://doi.org/10.3969/j.issn.1000-3428.2015.04.048
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    To solve the problem of insufficient resolution monitor videos,this paper presents a video image superresolution reconstruction method based on Video Fluid Model(VFM). A VFM records the region of a video object,as well as the pixels mapping in time domain. Denoising and resolution improving can be achieved by filtering and splicing pixels in VFM regions of different time. VFM is established based on isochromatic line firstly,and video denoising is carried out. The starting frame is selected as a reference image and flow tracking replenished are selected for interpolation frame by frame. The replenished FT is stretched to the first frame,referring to the FT adjacent. Experimental results show that Peak Signal to Noise Ratio(PSNR) gained by this method is about 1 dB to 4 dB higher than other methds,such as Maximum A Posteriori & Projection(MAPP) and Gradient Projection(GP).
  • LIAN Xiaocong,ZHOU Wei,DUAN Zhemin,LI Rong
    Computer Engineering. 2015, 41(4): 257-262. https://doi.org/10.3969/j.issn.1000-3428.2015.04.049
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    In the latest video compression standard,a new 8-tap Motion Estimation (ME) interpolation filtering is adopted in High Efficiency Video Coding(HEVC). Although the new 8-tap filter can improve the precision compared with the 6-tap interpolation filter used in H. 264/ AVC,it also increases the Very Large Scale Integration(VLSI) efficient area. A high performance VLSI architecture for HEVC interpolation filter is proposed. A fast and hardwareimplementation-friendly interpolation filtering algorithm is presented. Based on the fast algorithm,this paper designs and realizes the interpolation filter VLSI structure of the reconfigurable and the multiplexing of the cell block to reduce the efficient area of hardware. Experimental results show that, compared with the non-optimized VLSI architecture, the proposed VLSI architecture not only reduces the area and improves the working frequency,but also saves a lot of RAM. It can support the real-time processing of 4:2:0 format 3 840 ×2 160 video sequences.
  • WANG Aixia,ZHAO Yue
    Computer Engineering. 2015, 41(4): 263-266,272. https://doi.org/10.3969/j.issn.1000-3428.2015.04.050
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    In the super resolution reconstruction,a key step is the video motion estimation. Compared with other methods,matching algorithm based on features of video has higher robustness. However,the accuracy of this kind of methods is affected by the position and selection of feature points. To overcome this problem,this paper introduces the particle filtering into the motion estimation to reduce the matching error. The main disadvantage of the particle filtering is particle degeneracy. In this paper,an extended Kalman filtering is used to general the proposal distribution,and an Unscented Kalman Filtering(UKF) is used to refine particles. Experimental results show that,compared with other eight classic filtering algorithms, the proposed algorithm has much better performance, and for the super resolution reconstruction issue,the proposed algorithm can estimate the motion more accurately.
  • WANG Yingbo,NIE Nana,WANG Mingze,LI Zhongxue
    Computer Engineering. 2015, 41(4): 267-272. https://doi.org/10.3969/j.issn.1000-3428.2015.04.051
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    At the mine tailings’ characteristics of stochastic fluctuation and nonlinear,and its safety prediction can be affected by many factors,a prediction model for mine tailings is put forward by adopting Modified fruit Fly Optimization Algorithm of the Generalized Regression Neural Network ( MFOA-GRNN ). The method introduces the global optimization characteristics of MFOA to optimize the parameter of GRNN,while using correlation analysis to select the mine tailings safety evaluation to achieve forecast. Taking Liaoning Benxi Nanfen mine tailing as research instance to fit forecast,it shows that combining MFOA with GRNN is beneficial to select the smoothing factor and compared with prediction accuracy 70% of the FOA-GRNN model,MFOA-GRNN model prediction accuracy is as high as 100% and has higher prediction precision and stronger applicability.
  • XU Tailong,XUE Feng,GAO Xianhe,CAI Zhikuang,HAN Shaoyu,HU Xueyou,CHEN Junning
    Computer Engineering. 2015, 41(4): 273-276,283. https://doi.org/10.3969/j.issn.1000-3428.2015.04.052
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    An all digital fast-locking Successive Approximation Register-controlled Delay-Locked Loop(SARDLL) with wide-range operating frequency and constant acquisition cycles is presented for the clock synchronization of Dynamic Voltage / Frequency Scaling (DVFS) System-on-Chip (SoC). The improved resettable Digitally Controlled Delay Line (DCDL) scheme is adopted to effectively solve the harmonic lock problem and zero-delay problem of the conventional all digital SARDLL,meanwhile reduces the hardware overhead and increases the maximum operating frequency. The presented all digital SARDLL is implemented using the TSMC-65 nm CMOS standard cell library. Based on the typical corner and 25℃,the post-layout simulation results show that the operating frequency range is from 250 MHz to 2 GHz,the lock time is 18 cycles of the input clock signal and the power consumption is 0. 4 mW at 2 GHz and 1. 2 V supply voltage.
  • ZHANG Jiandong,LI Yizhe,LIU Jieling
    Computer Engineering. 2015, 41(4): 277-283. https://doi.org/10.3969/j.issn.1000-3428.2015.04.053
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    Inertia Navigation System(INS) can not output dynamic data when plane is not moving. Simulation of INS can solve this problem. In the avionic system simulation,the inertial navigation logic simulator interconnects to bus controller and other avionic or non-avionic subsystem using 1553B bus. It receives exterior incentive data through Ethernet. Using multi-thread can make main INS and backup INS operate respectively. The structure of hardware and the design of software is expatiated. After establishing flight attitude model and navigation position model,the simulator can simulate different kinds of logic sub-process of INS. The test and debug of avionic simulation system proves that,this simulator can receive flight information and fault state from exterior incentive source by rule and line,send position data and pose data of the plane to bus controller periodically after resolving,execute INS logic in the avionic detail design document and send INS state to bus controller.
  • LI Longshu,WANG Yating
    Computer Engineering. 2015, 41(4): 284-287,293. https://doi.org/10.3969/j.issn.1000-3428.2015.04.054
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    The research of combinatorial test always focuses on how to generate a minimum set of test cases,but which rarely comes to weight values of parameters. This paper proposes an algorithm based on In-Parameter-Order ( IPO) strategy to solve the problem of generating pairwises combinatorial test case set with weighted parameter. The algorithm makes some improvements on three factors which influence the performance of IPO strategy,including the order of expending of expanding parameter,the order of expending the existing test cases and the choose of the value of expanding parameter. In addition,after expending all parameters,it uses reduction algorithm processing the test set of this moment to simplify further. Finally,it gets the test set according to the descending order of weight values of test cases. Experimental result shows that this method not only can reduce the generation number of test cases,but also can solve the problem of weight values of parameters,which can more effectively reduce the cost of test in practical applications.
  • MENG Xiaohua,QIN Dasheng,ZHENG Dongqin,ZHOU Yuyu
    Computer Engineering. 2015, 41(4): 288-293. https://doi.org/10.3969/j.issn.1000-3428.2015.04.055
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    Molecular dynamics simulation has advantages dramatically superior to both theoretical analysis and experiments. However,due to the extremely high cost of computation resources during the simulation of a large number of Carbon Nano Tube(CNT) particles,typical CPU serial algorithm implementation is non-efficient and slow. A Compute Unified Device Architecture(CUDA) based parallel algorithm of CNT molecular dynamics is proposed in this paper to take advantage of the data parallelism of Graphic Processing Unit (GPU). A CNT is divided to several blocks and processed parallel in the GPU. Experimental results show that the algorithm can obtain a speed-up more than 10 times to the CPU serial algorithm in a low-configured graphics card that has only 16 GPU stream processors.
  • CHEN Ruifeng,FANG Luping,PAN Qing,CAO Ping,GAO Kun
    Computer Engineering. 2015, 41(4): 294-299. https://doi.org/10.3969/j.issn.1000-3428.2015.04.056
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    For the traditional ultrasound system is lack of three-dimensional anatomical structures in the image information as well as commercial medical image analysis and visualization software is very expensive,develops an ultrasound inspection system which has comprehensive characters of the three dimensional surface model and twodimensional real-time ultrasound image and their spatial relationships. This system is based on an open source medical image processing and visualizing software and the commercial electromagnetic tracking system, ultrasonic imaging system,which transmits the image and tracking data with each other following OpenIGTLink protocol in the local area network. This system is mainly composed of the ultrasound image information sharing module,ultrasound visualization module,ultrasonic probe real-time tracking module and 2D / 3D registration and integration module. The experimental results show that the system can be initially applied to the clinical education and diagnosis. There are three major advantages of this ultrasound inspection system,namely cheapness,scalability,maintenance.
  • GAO Mingming,NAN Jingchang,LIU Yue
    Computer Engineering. 2015, 41(4): 300-305. https://doi.org/10.3969/j.issn.1000-3428.2015.04.057
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    In order to improve the communication quality,this paper proposes a new,accurate,and complexity-reduced PLTC(parallel-LUT-TMP-CIMT) model according to the memory effect and nonlinearity effect characteristics of the radio frequency power amplifier in modern wireless communication system. This model is composed of a Look- up Table (LUT),a Triangular Memory Polynomial(TMP) and a Cross Items between Memory Times(CIMT),which are all connected in parallel. PLTC model is applied to model the behavior of the power amplifier model and the digital predistortion. This paper uses the 16QAM signal to drive a strongly nonlinear Doherty amplifier to verify the performance of the new model. Appling PLTC model in predistortion,PLTC model can reduce the Adjacent Channel Power Ratio (ACPR)by almost 22 dB. Compared with the MP model,GMP model and LMEC model,the result shows that PLTC model can acquire better modeling accuracy and linear effect and can greatly reduce the calculation coefficient.
  • LIU Jie,YAN Qingdong,TANG Zhenghua
    Computer Engineering. 2015, 41(4): 306-310. https://doi.org/10.3969/j.issn.1000-3428.2015.04.058
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    Through improving the traditional Vector Field Histogram (VFH) algorithm,a kind of outdoor obstacle avoidance planning algorithm for laser radar is proposed. Based on the laser radar and adaptive threshold,through the planning of the target course,the algorithm gets the real-time obstacle avoidance direction of the robot. When there are obstacles between the robot and the target point,the robot obtains the target heading with the maximum threshold. When between the robot and the target point without obstacles,the minimum threshold is used for robots which do not collide with obstacles. Simulation result shows that,when the robot speed is below 0. 8 m / s,it can be safely and smoothly through the complex obstacle area,gets to the goal;Otherwise,the robot gets to the goal with slight rub.
  • GAO Jinwei,MO Pengfei,YANG Jun,CHEN Zhijian
    Computer Engineering. 2015, 41(4): 311-315. https://doi.org/10.3969/j.issn.1000-3428.2015.04.059
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    Signed integer division instruction takes 6 ~ 38 cycles to complete in general micro-processors. By using the original operands for division without abs and negation process,3 cycles of latency can be reduced which will effectively improve the division performance of processor. This paper focuses on complement no-restoring division and its application, as well as proof on integer division. This paper does a research in quotient correction and its reasonable solution and also implements the division device. Experimental result shows that the device is only 12 687 μm2 in TSMC 130 nm process and can complete a 32 bit signed integer division in only 2 ~34 cycles,which means a performance improvement of 35% at a cost of only extra 16% area.
  • LV Xingsheng,LI Guangshun,WU Junhua
    Computer Engineering. 2015, 41(4): 316-321. https://doi.org/10.3969/j.issn.1000-3428.2015.04.060
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    Network-on-Chip(NoC) mapping algorithm has significant impact on system power consumption,reliability and other performances. A new Multi-objective Mapping Immune Algorithm based on Energy and Reliability(MMIAER) is proposed to decrease power consumption and increase system reliability without additional overhead added. The MMIAER is constructed by designing a new antibody initialization operator and a new mutation operator based on basic immune algorithm. The new antibody initialization operator of MMIAER generates the initial antibodies by greedy algorithm,and therefore,the quality of the initial solutions is improved. The new antibody mutation operator reduces the communication distance and optimizes the solutions through exchanging positions of Intellectual Property(IP) cores,and therefore,the new antibody mutation operator decreases the degradation risk due to the randomness. With the dynamic character of the network,a new power consumption model is proposed to make the calculation of power consumption more accurately. Simulation results indicate that the MMIAER can decrease the power consumption and increase the system reliability effectively.