15 April 2013, Volume 39 Issue 4
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Computer Engineering. 2013, 39(4): 1-4. https://doi.org/10.3969/j.issn.1000-3428.2013.04.001
To overcome the channel fading and improve the anti-interference capability in free-space optical communication, a coded Pulse Position Modulation(PPM) photon-counting based iterative demodulation scheme by utilizing Soft-input Soft- output(SISO) for single data stream is proposed. On the assumption of shot noise limited Poisson channels, the iterative demodulation algorithm is derived and on the basis of it, a simplified scheme is proposed for 4-ary PPM. The numerical results under the conditions of Repetition Code(RC) and Serial Concatenated Code(SCC) also with analysis of system performance are illustrated. The simulations show that the scheme can provide a relatively good system Bit Error Rate(BER) performance with low computational complexity and is easy for hardware realization.
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Computer Engineering. 2013, 39(4): 5-8. https://doi.org/10.3969/j.issn.1000-3428.2013.04.002
In the research of image encryption application, in order to resist the attacks, it needs to construct more chaotic sequence. Aiming at this problem, this paper studies the quadratic problem of quadratic function in unit area. The study finds that, a large number of the quadratic mapping is Li-Yorke chaos under certain conditions, some special cases is Devaney chaotic. It discusses chaos condition when unit area of the quadratic function value is less than 1, draws approximate area of control point which can generate chaos, computes cycle point of quadratic function in unit area and Lyapunov exponent, and generates a chaotic sequence which is available for image encryption. Experimental results show that constructing chaotic sequence by the quadratic curve for image encryption has a good result.
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Computer Engineering. 2013, 39(4): 9-13,17. https://doi.org/10.3969/j.issn.1000-3428.2013.04.003
Aiming at the vehicle routing problem with hard time windows and multiple fuzzy characteristics, a multi-objective fuzzy expected model is designed based on fuzzy credibility theory, and an adaptive hybrid Multi-objective Particle Swarm Optimization(MOPSO) is proposed to solve the fuzzy vehicle routing model. The algorithm puts forward a particle encoding method according as phase-space, and designs a double archiving mechanism which stores the non-dominated solutions and excellent infeasible solutions separately. It also introduces adaptive strategies on local search, mutation and selection for particle global guide. The compareative experiments with multi-objective evolutionary algorithm verify that the method is capable of getting more excellent Pareto sets.
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Computer Engineering. 2013, 39(4): 14-17. https://doi.org/10.3969/j.issn.1000-3428.2013.04.004
A Mandarin-English general phonetic alphabet?——Human Computer Speech Interaction Phonetic Alphabet(HCSIPA), in which the articulation manner and place are applied for construction criterion, is proposed in bilingual speaker based Mandarin-English mixed Text to Speech(TTS). A Mandarin-English common question set suitable for HCSIPA is constructed in Mandarin-English mix clustering. Its construction target is to increase the distinguishing between Mandarin and English in the decision tree structure. The result verifies the HCSIPA can increase the mixing with pronunciation unit of Mandarin and English, to reduce the timbre gap caused by language gap. The mixed TTS based on HCSIPA can synthesize the speech of Mandarin and English with a high quality, and the quality decline to single language synthesis caused by mix of Mandarin and English is not obvious.
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Computer Engineering. 2013, 39(4): 18-21,31. https://doi.org/10.3969/j.issn.1000-3428.2013.04.005
The inter-cluster interference and transmission power wasting exist in the Low Energy Adaptive Clustering Hierarchy(LEACH) protocol because of the independence of Time Division Multiple Access(TDMA) scheduling between neighbor cluster-heads. This paper proposes an Adaptive Power Control and Scheduling(APCAS) algorithm based on sink node to reduce the energy wasting and inter-cluster interference through monitoring Scheduling and Power Level(SAPL) table of neighbor cluster-head by the cluster-head to arrange adaptively the SAPL table. Simulation results show that this algorithm can effectively reduce inter-cluster interference by 50 percent and the power wasting.
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Computer Engineering. 2013, 39(4): 22-26,35. https://doi.org/10.3969/j.issn.1000-3428.2013.04.006
Aiming at the problem of wood veneer defect recognition with a texture, noise jamming and complex background, this paper proposes an improved active contour model. This model is combined with the respective advantages of the Geometric Active Contour(GAC) model and the active contours without edges model. It solves the model with a dual formulation of the weighted TV-norm and obtains a fast algorithm. Experimental results show that the model can be competent for the detection of veneer which contains multi knots and complex texture background. The algorithm has less computation, faster identification of veneer defects.
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Computer Engineering. 2013, 39(4): 27-31. https://doi.org/10.3969/j.issn.1000-3428.2013.04.007In order to improve the task processing performance of data layer, this paper presents a method to generate the tasks. The scripts of tasks are generated in accordance with the load characteristics or special requirements. By analyzing database running log and trace information, it gets the data processing tasks corresponding resource consumption patterns and processing performance. Test results show that this method can simulate the practical application of the system implementation, thus accesses to server resources occupancy linear eliminate the error between the acquired resources occupancy rate and the actual resources occupancy. This data can provide the basis for cloud computing platform to achieve optimal allocation of resources and computing power in accordance with the demand, and provide a basis for capacity planning of the database server, the storage structure design, the key features of the design and performance optimization.
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Computer Engineering. 2013, 39(4): 32-35. https://doi.org/10.3969/j.issn.1000-3428.2013.04.008In order to meet the needs of mass data storage, this paper proposes a distributed cache strategy in cloud storage based on Solid State Disk(SSD) and low power consumption. This strategy achieves the virtualization among different storage mediums, combines the cache and storage of the hot spot data together, and migrates the hot spot data among different storage mediums. The strategy also resolves the problems of the consistency of the hot spot metadata and the dynamic load balancing among the storage servers. Load pressure test indicates that the distributed cache strategy in cloud storage system based on SSD can improve the read peak rate by about 86%, and improves the system throughput effectively.
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Computer Engineering. 2013, 39(4): 36-38,43. https://doi.org/10.3969/j.issn.1000-3428.2013.04.009Aiming at the problem of data replicas management time-delay in the cloud storage system, this paper puts forward a distributed replica management model for unstructured data. The model reduces the system energy consumption through carefully designed rack-selection algorithm, which is the technical basis of green data center. To improve system performance and balance utilization of resources, the model uses a multi-linear-hashing algorithm, which can balance the data replicas distribution in different nodes intelligently. Simulation experimental results show that this model can reach higher storage and load balance compared with traditional global mapping method, it has excellent system performance, scalability and availability.
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Computer Engineering. 2013, 39(4): 39-43. https://doi.org/10.3969/j.issn.1000-3428.2013.04.010Aiming at the difficulties of the form transferring on large datasets to get reducts, a same element conversion reduction algorithm based on discernibility matrix and discernibility function is put forward. It uses discernibility matrix to keep all classification information of data set, and discernibility function constructs the mathematical logic form from the classical information. The algorithm begins from lower rank of Conjunctive Normal Form(CNF) into Disjunctive Normal Form(DNF). According to the same element conversion algorithm and high element absorption algorithm, if higher ranks are absorbed, the algorithm can return; else the algorithm can enter itself to next circle. Calculation results show that this algorithm greatly reduces the once scale of transform, neatly uses the mature recursive algorithm and works compactly and effectively.
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Computer Engineering. 2013, 39(4): 44-47. https://doi.org/10.3969/j.issn.1000-3428.2013.04.011Probabilistic threshold top-k query calculation sum of the probability of the tuple ranked top-k and return the tuples whose sum of the probability are at least p. But top-k query does not take x-tuple as a whole, thus a new top-k query semantic probabilistic threshold x-top-k query is defined and an algorithm is given to process it, which uses dynamic method to acquire sum of the probability of the tuple, then process aggregate probabilities with top-k query. It uses several pruning methods like the upper bound method and so on to optimize the algorithm. Experimental result shows that the algorithm return the answer set for scanning about 60% of data set, and it demonstrates that the algorithm is efficient.
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Computer Engineering. 2013, 39(4): 48-51. https://doi.org/10.3969/j.issn.1000-3428.2013.04.012Aiming at the problem that rough set and the main machine learning algorithms can not efficiently handle continuous data, this paper presents an improved CACC algorithm for discretization of the continuous data. This algorithm adopts the CACC standard to select breakpoints to increase constraints on data inconsistency, thereby reducing the amount of information loss. Simulation results show that the algorithm outperforms the corresponding algorithms, such as Modified Chi2, Extent-Chi2, CAIM, CACC, through the C4.5 and SVM algorithm validation, the maximum amplitude of data recognition rate and accuracy is increased by 8%.
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Computer Engineering. 2013, 39(4): 52-57. https://doi.org/10.3969/j.issn.1000-3428.2013.04.013Aiming at the problem of the mixed tracking and fusion problem of linear system and nonlinear observation, a multi-radar data fusion method based on distributed Best Linear Unbiased Estimation(BLUE) filter is provided under the premise that three- dimensional BLUE filter of constant acceleration target motion model is derived. In which, the BLUE target states at cell radar are given in Cartesian coordinates. All the target states estimations are fused at fusion center. The advanced technique is compared with the traditional Nested Conditioning(NC) debiased conversion states fusion method and the Modified Measurement Conditioned(MMC) unbiased conversion states fusion method by taking the position Root-mean-square Error(RMSE), velocity RMSE and Average Normalized Estimation Error Squared(ANEES) as the fusion performance evaluation criterion. Simulation results show that the advanced technique is not sensitive with the variety of the process noise and measurement noise. Its position and velocity RMSE are smaller than the corresponding of NC and MMC based method. It has high fusion accuracy and reliability, even if the errors become larger.
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Computer Engineering. 2013, 39(4): 58-61. https://doi.org/10.3969/j.issn.1000-3428.2013.04.014According to the analysis of the process scheduling algorithm of Linux kernel 2.6.22, through the information getting from Performance Monitor Unit(PMU), this paper puts forward three performance indexes CMR, CRR and OCIP to describe the process behavior of cache contention. On the basis of this, it uses polling algorithm to optimize the process scheduling in order to reduce the cache contention of Last Level Cache(LLC). Benchmark test results show that this algorithm can improve about 6% performance when the system load is high.
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Computer Engineering. 2013, 39(4): 62-65. https://doi.org/10.3969/j.issn.1000-3428.2013.04.015In order to monitor illegal operations in semantics of drivers loaded by users, this paper introduces Monitoring Server(MS) to Minix. MS intercepts messages and analyses them by strategy data and functions, and draws a conclusion whether the driver takes a malicious action, that is to send out error control or data messages. Experimental results show that MS does a good job and system efficiency drops little when MS is realized in kernel.
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Computer Engineering. 2013, 39(4): 66-70. https://doi.org/10.3969/j.issn.1000-3428.2013.04.016This paper uses the top-down analysis method and considers the characteristics of the elements in enterprise Service- oriented Architecture(SOA) model, it proposes a method to identify service components based on business model. It can generate relevance matrix by activity relevance formula based on the association between elements in the business process model. Then analyzing the matrix using the cluster algorithm, it gets the high-cohesion, low-coupling and reusing business components. Example analysis results show that this method can identify service components with optimizer comprehensive measuring index than service identification method based genetic algorithm and enterprise business component method based clustering analysis.
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Computer Engineering. 2013, 39(4): 71-74. https://doi.org/10.3969/j.issn.1000-3428.2013.04.017Against the semantics of XML Access Control Markup Language(XACML) policies, conflict and other issues, this paper provides description logic-based formal methods, formalizes XACML policy target, rules, rules combination algorithms and policy conflict resolution algorithm, and puts forward the rules conflict detection method based on the description logic. Analysis result shows that this method facilitates strategic expansion, and enhances the XACML semantics of expressive power and reasoning ability.
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Computer Engineering. 2013, 39(4): 75-77,81. https://doi.org/10.3969/j.issn.1000-3428.2013.04.018In order to solve the problem of inflexible access control and lack of dynamic task allocation for workflow, this paper presents a new workflow access control model. It integrates both users and roles authorization on workflow tasks in two level of modeling stage and instance stage, and also designs dynamic user assignment rules for the model by introducing the load equilibrium-based user assignment strategy on the user busy factor. Analysis result shows that this model can produce dynamic user assignment according to history executive condition, and improve workflow’s executive efficiency.
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Computer Engineering. 2013, 39(4): 78-81. https://doi.org/10.3969/j.issn.1000-3428.2013.04.019Most processor adopts the inclusive cache hierarchy, which requires that the contents of the upper level cache are resident in last level cache. In-depth tests show that the Last-level Cache(LLC) block replacement algorithm has great performance impact on memory system performance. This paper proposes a new LLC cache replacement algorithm, called PLI, to select the best Least Recently Used(LRU) replacement block. Simulation results show that PLI has average 7% performance speedup over traditional approach.
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Computer Engineering. 2013, 39(4): 82-84,89. https://doi.org/10.3969/j.issn.1000-3428.2013.04.020This paper puts forward a method to address on-chip Memory Management Unit(MMU) by hardware logic. To manage a 9 728 Byte jumbo frame’s storage, two levels of linked lists are used to organize descriptor output queue table in designing a switch controller. The first level is the TXQ linked list, which is used to maintain frame priority order for each port. And the second level is the buffer tag linked list, which is used to maintain the order of the buffer pages corresponding to each frame. Simulation experimental results show that two levels of linked lists can organize descriptor effectively.
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Computer Engineering. 2013, 39(4): 85-89. https://doi.org/10.3969/j.issn.1000-3428.2013.04.021In view of the characteristic and demand of nodes localization in mobile sensor networks, this paper improves the classical particle filter in some significant aspects, and proposes a Particle Filter based Nodes Localization(PFNL) algorithm. This new localization algorithm overcomes the limitations of the classical particle filter and cuts down the requirement of node’s computing and storage capability. Simulations show that PFNL possesses higher localization precision than other two typical localization algorithms under the same simulation parameters.
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Computer Engineering. 2013, 39(4): 90-93,99. https://doi.org/10.3969/j.issn.1000-3428.2013.04.022The probabilistic routing algorithm in Delay Tolerant Network(DTN) called PROPHET, determines whether to forward messages according to the encounter probability between node and destination. However encounter probability can not accurately show the successfully delivered probability. Aimming at this problem, PROPHET-ACA is proposed, and it combines the fundamental of ant colony algorithm with probabilistic routing. The rule both in pheromone update and in message transmission is modified. Simulation results show that compared with to the PROPHET, in PROPHET-ACA, the delivery probability of message is obviously increased higher and the overhead ratio is decreased.
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Computer Engineering. 2013, 39(4): 94-99. https://doi.org/10.3969/j.issn.1000-3428.2013.04.023To meet the need of transmitting video in Unmanned Aerial Vehicle(UAV) Ad Hoc networks, a light Media Access Control(MAC) protocol is lay out which can provide the lowest access delay, named LADP. LADP is composed of multi-RTS and simple CTS in structure considering high dynamicity and low density of the UAV networks, and coordinated-competing mechanism is applied. All that make LADP simple and low bandwidth-consumption. Simulation results show that LADP can provide reliable guarantee of access delay under limited load for UAV network when λ≤0.8, and the maximum access delay is below 55 ms.
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Computer Engineering. 2013, 39(4): 100-104,108. https://doi.org/10.3969/j.issn.1000-3428.2013.04.024This paper targets on the problem which mobile nodes lose trusts after crossing domains in Internet of Things(IoT), and references current researches on networking trust and Wireless Sensor Network(WSN). It raises network model, service model and reputation model of reputation system for cross-domains nodes in IoT. It describes a series of processes which give trust transfer and initialization. It gives methods of reputation initialization, update, integration and sharing via Gaussian Reputation for Sensor Network(GRFSN) model. Simulation results show that in the context of IoT, it has higher convergence speed than the traditional GRFSN model in WSN and it also keeps the attribute of detecting malevolence nodes.
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Computer Engineering. 2013, 39(4): 105-108. https://doi.org/10.3969/j.issn.1000-3428.2013.04.025Aiming at the problems of the characteristics of low transmission frequency and rate, limited bandwidth and strong multi-path effect in underwater acoustic communication, optimal equalization technology in underwater acoustic system is designed. It combines LDPC code, direct-sequence spread spectrum and DQPSK. And LDPC-DQPSK based on soft decision decoding is a method to overcome high error rate performance of traditional hard decision. LMS and RLS algorithm are investigated, analysing the system BER performance of different adaptive equalization scheme based on the characteristics of underwater acoustic channel. Experimental results show that the proposed underwater acoustic system can obtain improved error rate in lower SNR, saving the transmission bandwidth.
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Computer Engineering. 2013, 39(4): 109-112. https://doi.org/10.3969/j.issn.1000-3428.2013.04.026Performance of Transmission Control Protocol(TCP) and utilization of the network resources is low when the TCP operates in wireless data communication. Aiming at this problem, this paper proposes an improvement algorithm of TCP to adapt the wireless environment. The data sender adopts available bandwidth estimation algorithm in order to optimize slow start threshold and congestion window, and cooperates with the router which is configured with the function of Explicit Congestion Notification(ECN) to distinguish the characteristics of packet losses. At the same time, the sender takes advantage of the wireless packet loss rate estimation to adjust the TCP segment size adaptively. Simulations results show that the throughput of modification of TCP outperforms TCP-Jersey by 30%, and TCP_SACK by 59% approximately when the bit error rate is 1E–4.
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Computer Engineering. 2013, 39(4): 113-117. https://doi.org/10.3969/j.issn.1000-3428.2013.04.027Based on the wide support of 802.11x series standards to orthogonal mutli-channel technology, this paper introduces the simulation requirement in wireless networks, based on multi-interface multi-channel(MIMC), for lower layer(data link and physical layers) protocols. The simulation shortage for MIMC model support in NS-2 is summarized. Then the basic methods and principles for MIMC extensions to NS-2 are elaborated based on some existing schemes. The classification and analyses of extensions are illustrated and some contrastive analyses about MIMC models are given at length.
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Computer Engineering. 2013, 39(4): 118-122. https://doi.org/10.3969/j.issn.1000-3428.2013.04.028According to the characteristics of disaster awareness network, this paper proposes a method to reduce network energy consumption under security network reliability. The monitor domain is divided into several sensor grids which have appropriate radius, so as to reduce the transmission distance of the node information. It adopts reasonable dormancy mechanism to reduce the perception of network energy consumption. Simulation results show that this method can effectively reduce the network energy consumption and prolong the network life when it is applied in the tasks network such as disaster awareness.
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Computer Engineering. 2013, 39(4): 123-127. https://doi.org/10.3969/j.issn.1000-3428.2013.04.029Since IEEE 802.15.5 Low Rate Wireless Personal Area Network(LR-WPAN) standards lack load balancing design, a double energy efficient optimization method is proposed for LR-WPAN Mesh network and reasonable judge elements of energy efficiency is introduced for Adaptive Tree(AT) and Topology-guided Distributed Link State(TDLS) router of LR-WPAN Mesh network to optimize the topology and router choice. Experimental results show that the double energy efficient optimization method can prolong the network lifetime by about 97% and make the consumption of the network more balance.
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Computer Engineering. 2013, 39(4): 128-131. https://doi.org/10.3969/j.issn.1000-3428.2013.04.030Aiming at the sum probability distribution problem of the interplation function produced by macrocosm approximation of addition modulo 2n with XOR, this paper utilizes the definition of the probability distribution, and gives out the computation formula of the probability distributions of two noise functions, through counting the number of variables satisfying the conditions. Then this paper gives out the computation formula of the square sum of the probability distribution of the sum of two noise functions, which reduces the computation complexity from O(24n) to O(1).
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Computer Engineering. 2013, 39(4): 132-136. https://doi.org/10.3969/j.issn.1000-3428.2013.04.031According to the certificateless signcryption scheme proposed by Zhu Hui et al, this paper proposes a strongly secure Content Extraction Signature(CES) scheme without bilinear operations. The user’s public key is bound to the partial private key generation algorithm and signature algorithm, which reduces the possibility of user’s public key substitution attack. By using secure hash function of a non-collision, it can resist existence unforgeable under adaptive chosen-message attacks. Based on Discrete Logarithm Problem(DLP) is intractable, and its security is proved under Random Oracle Model(ROM). Compared with similar programs, the scheme’s signature and interception algorithm reduces one exponentiation computation, the computational efficiency is improved.
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Computer Engineering. 2013, 39(4): 137-139. https://doi.org/10.3969/j.issn.1000-3428.2013.04.032This paper investigates the multinomial relativity of binary No sequences by using the conception and properties of trace functions from the field F2n to the subfield F2m. The multinomial relativity function of No sequences of period 2n–1 is P–1(2mt–T) , and its value field is {P–1(2mt–T)︱t = 0,1,…,(T–1)r∕(2m–1)}∪{1}. In this correspondence, it shows that the multinomial relativity function of No sequences has more than three values, so the multiple access interference of No sequences is more intensive than Kasami sequences.
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Computer Engineering. 2013, 39(4): 140-145. https://doi.org/10.3969/j.issn.1000-3428.2013.04.033Aiming at the lack of dynamic adaptive capacity of existing trust prediction model and security problem of the interaction between agents in services computing environment, this paper proposes a new trust prediction model in oriented-service computing combining human cognitive behavior. It introduces a direct trust value and reputation of the recommended values. In Trust Prediction Model for Service-oriented Computing(SOC-TPM), it creates the credibility of the relationship model by a reputation tree and analysis the historical interaction records based on the timestamp to solve the problems of lacking dynamic adaptation capacity in traditional prediction model. Simulation results show that compared with J?sang model and Beth model, trust prediction accuracy and ARER of the model are respectively increased by 27% and 47%.
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Computer Engineering. 2013, 39(4): 146-150. https://doi.org/10.3969/j.issn.1000-3428.2013.04.034In order to enhance reliability in delegations and ensure system security, this paper proposes a delegation model based on trust degree and secure strategy of collaboration. Trust qualifications, trust experiences and trust recommendations are utilized to comprehensively compute trust values, and trustworthy candidates with higher values are chosen. Mutually exclusive role constraints are adopted to indirectly enforce division policy of collaboration, and the most appropriate delegate is chosen in the secure collaborative environment. Compared with existing models, theoretical analyses and experimental results show that the model can efficiently reflect reliability in delegations, and it satisfies requests of system security.
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Computer Engineering. 2013, 39(4): 151-153. https://doi.org/10.3969/j.issn.1000-3428.2013.04.035This paper analyzes the security of Li et al’s group signature scheme. In this scheme, group manager can get any user’s secret key, thus it can forge any user’s group signature, and forger can get a valid group signature of any user on any message, which leads to the scheme can be forged universally. Two attacks are presented, which shows the scheme does not satisfy traceability and is not secure.
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Computer Engineering. 2013, 39(4): 154-158. https://doi.org/10.3969/j.issn.1000-3428.2013.04.036In order to solve the problems of high false alarm rate and fail rate in intrusion detection system of Computer Integrated Process System(CIPS) network, this paper takes advantage that Genetic Algorithm(GA) possesses overall optimization seeking ability and neural network has formidable approaching ability to the non-linear mapping to propose an intrusion detection model based on Genetic Algorithm Neural Network(GANN) with self-learning and adaptive capacity, which includes data collection module, data preprocessing module, neural network analysis module and intrusion alarm module. To overcome the shortcomings that GA is easy to fall into the extreme value and searches slowly, it improves the adjusting method of GANN fitness value and optimizes the parameter settings of GA. The improved GA is used to optimize BP neural network. Simulation results show that the model makes the detection rate of the system enhance to 97.11%.
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Computer Engineering. 2013, 39(4): 158-164. https://doi.org/10.3969/j.issn.1000-3428.2013.04.037In view of network security situation awareness framework’s lack of a precise mathematical quantitative method to network information security risk assessment, a network risk assessment model based on network security situation awareness framework is proposed by combining DS evidence theory and Consultative Objective Risk Analysis System(CORAS). Network security threats information fusion and situation perception based on DS evidence theory, hierarchical risk quantitative analysis based on probabilistic risk analysis, and risk discrimination. Low earth orbit satellite communication network is taken as an example to make a simulation and assessment. Experimental results show the proposed model and method can effectively identify threat situation, and increase the accuracy of risk assessment discriminant.
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Computer Engineering. 2013, 39(4): 165-168,172. https://doi.org/10.3969/j.issn.1000-3428.2013.04.038This paper summarizes the schemes of typical targeted and universal steganalysis methods, and points out three challenges in this area: the detection of low embedding rate, the mismatch between the training image source and the test image source, and the ability to adapt unknown steganography algorithms. And it shows that steganalysis based on rich model and digital forensics are two research trends in the field. The former merges different features from different domains and then distinguishes between cover and stego-images by using ensemble classifier. The latter identifies the image type by using digital forensics in advance, and then detects the image by utilizeing stegoanalysizer of the corresponding type. So that the problem is solved and performance of detection is improved.
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Computer Engineering. 2013, 39(4): 169-172. https://doi.org/10.3969/j.issn.1000-3428.2013.04.039At present, most proxy blind signature schemes use first signed encrypted algorithm. The security is improved, but computation and communication complexities are greatly increased. To solve this problem, combining proxy blind signature scheme with proxy signcryption scheme, a randomized proxy blind signcryption scheme without paring computing is proposed. The random factor is used in the signcryption process. The results prove that this scheme meets all the features of proxy signature and blind signcryption, and the security is further enhanced.
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Computer Engineering. 2013, 39(4): 173-176,179. https://doi.org/10.3969/j.issn.1000-3428.2013.04.040Aiming at the issue of high risk of Database(DB) plaintext leakage, a DB encryption scheme based on Elliptic Curve Diffie-Hellman(ECDH) and Rijndael is proposed in this paper, which supports three kinds of key length, including 128 bit, 192 bit and 256 bit. The session key is generated by the private key and public key. The private key is independent of the Database Management System(DBMS), which can eliminate the possibility of key leakage from the database. An experiment is performed on the .Net platform. Experimental results show that the new scheme can resist exhaustive attack, differential attack, etc., and the maximum key space is 2256, and the encryption time, encryption efficiency and key sensitivity is desirable.
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Computer Engineering. 2013, 39(4): 177-179. https://doi.org/10.3969/j.issn.1000-3428.2013.04.041To deal with the key exposure problem in the designated verifier proxy signature, a forward secure designated verifier proxy signature scheme is proposed. The forward-secure thought is integrated into the new scheme in which the whole validity time is divided into T time periods, the public key always stays fixed while the private key updates as time goes. Experimental results show that the new scheme not only has some degree of improvement in terms of efficiency, but also realizes that even if the current proxy signer’s key is exposed, the adversary can not succeed in forging the valid proxy signature pertaining to the past which can effectively reduce the damage of key exposure.
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Computer Engineering. 2013, 39(4): 180-183,189. https://doi.org/10.3969/j.issn.1000-3428.2013.04.042The special access control requirements of EPC Information Service(EPCIS) in the supply chains are analyzed, and an EPCIS access control model based on Extensible Access Control Markup Language(XACML) is presented. The access control execution interface in the model can intercept the access requests by using the method intercepting technology, and produce the corresponding judgment context. Based on the user property, resource property, environment property and action property, which are included into the judgment context, the access control service component can dynamically assess the access requests. The secure communication component can effectively provide the real-time transmission for XACML authorization request/response messages, by combining the Security Assertion Markup Language(SAML) and the caching mechanism. The access control workflow indicates that the model can implement the flexible and variable deployment and management of the access control strategies, which is well fit for implement highly dynamic and heterogeneous access control function for the product information in the supply chains.
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Computer Engineering. 2013, 39(4): 184-189. https://doi.org/10.3969/j.issn.1000-3428.2013.04.043A hybrid data mining approach based on user relationships and attributes is proposed in this paper. The microblog user relationship network is built according to the microblog features. Small-world network theory is used to determine the user's center and generate a candidate set of opinion leaders based on user relationship. Through analysis on microblog user attribute, this paper builds opinion leader affect system, proposes D-means cluster algorithm, and acquires candidate set of opinion leaders. The final opinion leader is got on combination of the two candidate sets. Experimental results demonstrate that the proposed method outperforms more accurate and effective on mining opinion leader than the existing ones.
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Computer Engineering. 2013, 39(4): 190-193,198. https://doi.org/10.3969/j.issn.1000-3428.2013.04.044In order to recognize zombie fans of micro-blog, this paper proposes a new intelligent classification method based on the characteristics of registered usernames. Taking Sina micro-blog as research platform, by analyzing its giant user database, a standard matching library is constructed, and the user characteristics set is extracted to be trained and predicted with Supported Vector Machine(SVM) and Artificial Neural Network(ANN). Experimental results show that combing user characteristics, SVM and ANN can effectively solve the problem of classification of usernames, and the accuracy ratio of recognition is higher than 92%.
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Computer Engineering. 2013, 39(4): 194-198. https://doi.org/10.3969/j.issn.1000-3428.2013.04.045Aiming at the drawback that Local Fisher Discriminant Analysis(LFDA) algorithm and the Marginal Fisher Analysis(MFA) algorithm solve the problem of multimodal data classification and construct a reasonable neighborhood for each point. A local discriminant projection algorithm based on adaptive neighborhood selection is proposed in this paper. An adaptive algorithm to expand or narrow neighbor coefficient k is adopted to keep the local linear structure. So it perfectly detects the intrinsic geometric structure of manifold. The underlying idea of the new method is that the desired projection should make neighbors of the same class close and neighbors of different classes apart. Doing test on the ORL and the YALE face database, the results show that this algorithm can achieve higher recognition rate under different training samples.
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Computer Engineering. 2013, 39(4): 199-202,209. https://doi.org/10.3969/j.issn.1000-3428.2013.04.046Compared with Principal Component Analysis(PCA), L1-PCA has better robustness. But, there are some problems in the L1-PCA such as locally optimal solutions, computational complexity of rank. In order to solve the problems, the paper proposes a new algorithm of L1-PCA based on trace norm, it uses trace norm approximate to instead of matrix rank, and solves the problem that rank constraint has many local optimal solution, and the solution algorithm is based on Augmented Lagrange Multiplier(ALM) and applies it in noise reduction of images. Experimental results show that the image outline of this algorithm after doing noise reduction is clear and objects within the same class become more similar.
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Computer Engineering. 2013, 39(4): 203-209. https://doi.org/10.3969/j.issn.1000-3428.2013.04.047Because lack of labeled samples in acronym expansion recognition task, rule-based or supervised methods are unsuitable to find a proper phrase in sequential texts to explain a given acronym. A semi-supervised Conditional Random Field(CRF) is designed to make use of sufficient unlabeled samples and a few labeled samples. A supervised CRF model by a few labeled sequential samples is trained. Minimum sequential entropy is employed to learn relationship between samples without labels. A self training model is applied to analyzes the relationship between labeled and unlabeled samples. Experimental results show this model achieves the best performance of sequential F1(84.73%) against the state-of-the-art baselines including Support Vector Machine(SVM) and supervised CRF.
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Computer Engineering. 2013, 39(4): 210-213,218. https://doi.org/10.3969/j.issn.1000-3428.2013.04.048How to segment the occluded vehicle is a key problem in Intelligent Transportation System(ITS). But the available algorithms can not preserve the edge characteristics of vehicle. This paper presents a new occluded vehicle segmentation method based on corner feature. It chooses the frame difference method to extract object and uses the mathematical morphology to repair, introduces two geometric parameters to judge the overlapping type, combines Harris corner detection with the K-means algorithm to identify the corner points which is in the overlapping area, realizes the segmentation for overlapping vehicle according to the axial symmetry. Experimental results show that this method can keep the vehicle’s profile details information, and realizes the desired results.
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Computer Engineering. 2013, 39(4): 214-218. https://doi.org/10.3969/j.issn.1000-3428.2013.04.049Aiming at the problem that online planning can not meet the requirement of high real-time and low error at the same time in continuous states Partially Observable Markov Decision Processes(POMDPs), a forward-search algorithm called the Posterior Belief Clustering(PBC) is proposed in this paper. PBC analyzes the errors of a class of continuous posterior beliefs by KL divergence, and clusters these posterior beliefs into one based on errors of KL divergence. PBC calculates the posterior reward value only once for each cluster. The algorithm exploits branch-and-bound pruning approach to prune the posterior beliefs and/or tree online. Experimental results show that this algorithm can effectively reduce the size of the solving problem, eliminates repeated computation, and has good performance on real-time and low errors.
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Computer Engineering. 2013, 39(4): 219-221,225. https://doi.org/10.3969/j.issn.1000-3428.2013.04.050Incomplete pruning leads to inefficiencies for the search space with the same transaction set in parent-child node according to the traditional pruning strategy. This paper presents a parent-child equivalency pruning strategy which can prune the search space with the same transaction set in parent-child node. It effectively minimizes the search space and reduces the number of frequent items. The new maximal frequent itemset mining algorithm is completed based on new pruning strategy. Experimental results show that the new pruning strategy can shorten the time of mining maximal frequent itemset with the same support.
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Computer Engineering. 2013, 39(4): 222-225. https://doi.org/10.3969/j.issn.1000-3428.2013.04.051For the large scale of parameter select range, it costs many time to blindly search optimal parameters in a number of parameters, and is hard to get optimal parameters. In order to solve this problem, a Support Vector Machine(SVM) prediction algorithm based on improved Artificial Fish Swarm Algorithm(AFSA) is proposed in this paper. It makes improvement with AFSA, and uses the improved AFSA to make improvement with SVM. Experimental results show that compared with Genetic Algorithm(GA), Particle Swarm Optimization(PSO) algorithm, and basic AFSA improvement SVM, the mean square error is decreased to 2.51×10?3 of this algorithm, improves the prediction accuracy.
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Computer Engineering. 2013, 39(4): 226-229,233. https://doi.org/10.3969/j.issn.1000-3428.2013.04.052Compared with the Visible Light(VL) image, the Near Infrared Ray(NIR) image leads to fuzzy and insufficiency outline of face which is impact on the performance of face recognition. A new NIR and VL fusion algorithm based on score is proposed. Matching scores of NIR and VL face images are got by eigenface algorithm, and is to fuse the scores to get the final score. Experimental results show the effectiveness of the proposed method. The Equal Error Rate(EER) on CASIA HFB database is reduced from 4.65% to 3.80% and it is reduced from 0.55% to 0.38% on HITSZ Lab1 database.
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Computer Engineering. 2013, 39(4): 230-233. https://doi.org/10.3969/j.issn.1000-3428.2013.04.053Information redundancy and independent feature can lead to higher computational complexity and over fitting problem in machine learning. A filter feature selection algorithm based on coalitional game is proposed in this paper. The joint mutual information is utilized to measure the relevance between the coalition and target class, and Shapley value is used to evaluate the importance of each feature among the feature space. Experimental results show that under two kinds of classifier such as C4.5 and Support Vector Machine(SVM), the subset mean classification accuracy of this algorithm are 88.72% and 93.39%, and is higher than mRMR algorithm and ReliefF algorithm.
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Computer Engineering. 2013, 39(4): 234-238. https://doi.org/10.3969/j.issn.1000-3428.2013.04.054Aiming at the problems that the Quantum Genetic Algorithm(QGA) easily falls into local extremum, an improved QGA algorithm of quantum revolving gate is proposed. In order to achieve the goal of optimization solving, quantum bit probability amplitude is applied to the chromosome encoding, and quantum rotation gate is used to chromosome updating. The theoretical derivation proves that the proposed algorithm converges with probability 1, and the algorithm converges strongly to 1?ε. Comparing with double QGA, simulation results show that the algorithm increases complexity, the average time extension, but convergence times increase, convergence times of the function 1 increases from 3 to 7, and convergence times of the function 2 increases from 8 to 9.
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Computer Engineering. 2013, 39(4): 239-242. https://doi.org/10.3969/j.issn.1000-3428.2013.04.055Tracking algorithm based on RGB histogram is sensitive to the similarity color in background, leading to failure in tracking. In view of the above problem, a tracking algorithm based on blocking with multi-feature combination is proposed. This algorithm adopts K-S similarity measure in Edge Orientation Histogram(EOH) and RGB histogram, with adaptive combination to track object. Experimental results show that it has better performance than single feature as well as robust to occlusion.
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Computer Engineering. 2013, 39(4): 243-247. https://doi.org/10.3969/j.issn.1000-3428.2013.04.056Traditional path planning method exists the problem that the calculation is complex, efficiency is low, and has high error. In order to solve this problem, this paper proposes a real-time local path planning method for mobile robot based on Kinect. This paper uses RGB images and 3D images produced by Kinect to get the real-time peripheral dynamic environmental information of mobile robot, uses the fuzzy logic and information fusion technology to realize real-time path planning for the robot in dynamic environment, so as to solve the problem of robot target tracking and navigation. Experimental results show that this method has good stability and real-time.
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Computer Engineering. 2013, 39(4): 248-253. https://doi.org/10.3969/j.issn.1000-3428.2013.04.057This paper uses MapReduce parallel programming mode to make the Ant Colony Optimization(ACO) algorithm parallel and bring forward the MapReduce-based improved ACO for Multi-dimensional Knapsack Problem(MKP). A variety of techniques, such as change the probability calculation of the timing, roulette, crossover and mutation, are applied for improving the drawback of the ACO and complexity of the algorithm is greatly reduced. It is applied to distributed parallel as to solve the large-scale MKP in cloud computing. Simulation experimental results show that the algorithm can improve the defects of long search time for ant colony algorithm and the processing power for large-scale problems.
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Computer Engineering. 2013, 39(4): 254-257,262. https://doi.org/10.3969/j.issn.1000-3428.2013.04.058Aiming at the disadvantages of wavelets, which exist the absence of directions and cannot achieve the best approximation when deal with 2D signals. The idea of processing edge problem in directionlets is introduced. Sample matrix in directional filter banks is used to perform the rotation for images and presentation for two directions with angular, which makes the two directions project be vertical and horizontal direction. At the same time considering that wavelets are good at dealing with texture features, combine the direction transformation with wavelet transform further. The better presentation for diagonal information is achieved. Simulation experimental results show that the method can significantly improve the visual effect of the image.
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Computer Engineering. 2013, 39(4): 258-262. https://doi.org/10.3969/j.issn.1000-3428.2013.04.059For the complicated mode of the touched string, it is difficult to segment accurately based on the conventional image processing method, a touched string segmentation method is proposed based on machine learning, which includes training and segmentation. The segmentation knowledge between the characters is learned from an example database. The input touched string is processing via a Markov random field network to obtain a probability map, and the tradition image segmentation algorithm can be applied on the probability map to determine the split position. Experimental results on simulated touched string, overlapping string and the real touched hand writing string show that the algorithm is effectiveness.
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Computer Engineering. 2013, 39(4): 263-266,271. https://doi.org/10.3969/j.issn.1000-3428.2013.04.060For the text in the print Uighur character recognition system, especially for the difficult issue of conjoined section letter segmentation, an improved projection segmentation method is put forward. The index value of the baseline region pixels set to white(set the pixel index value to 255) is adopted, and its vertical projection is made. The projector to a value of 0’s gap is taken as a candidate tangent position. The threshold value is combined with the line height and width ratio of the blank gap statistics data’ average value is set to eliminate false segmentation. Experimental results prove that the method makes the piece paragraph segmentation of the correct rate further improved.
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Computer Engineering. 2013, 39(4): 267-271. https://doi.org/10.3969/j.issn.1000-3428.2013.04.061Based on the facts that natural images can be sparsely coded, and their basis functions are similar to the particular shapes of V1 simple-cell receptive fields and the sparse coefficients correspond to the response properties of visual neurons for the fixed patterns, a novel image fuzzy degree assessment method based on sparse representation is proposed. The flow chart of the proposed method is to divide the input image into no overlapped patches. The coefficient vectors and the visual attention weights of each patch are computed, and the fuzzy degree is represented by the linear superposition of the p-norm of sparse coefficient vectors and visual attention weights of each patch. Experimental results show that the proposed method is monotonic, robust to additive noises, and also consistent with human visual system.
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Computer Engineering. 2013, 39(4): 272-275,279. https://doi.org/10.3969/j.issn.1000-3428.2013.04.062To overcome the image blurring and ringing effect problem encountered in low bit-rate coding of images for wireless transmission, an efficient image compression algorithm via adaptive down-sampling and interpolation in wavelet domain is presented. At the encoding end, the image is transformed to wavelet domain, and the high frequency subbands are down-sampled adaptively according to their characteristics. The down-sampled image is coded by the wavelet tree-based Wavelet Difference Reduction(WDR) algorithm. At the decoding end, the decoded high frequency subbands are enlarged by using an edge direction based interpolation method, and the reconstructed image is post processed by a strong edge based adaptive filter to eliminate the ringing effect. Experimental results show that compared with the spatial down-sampling based compression algorithm, the proposed algorithm possesses higher decoding quality of images at low bit-rate, thus effectively alleviates the image blurring and ringing effect.
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Computer Engineering. 2013, 39(4): 276-279. https://doi.org/10.3969/j.issn.1000-3428.2013.04.063In accordance with existing problems of data transmission and network communication of distributed data acquisition system, a DataSocket communication model based on the principle of asynchronous parallel algorithm is presented. According to the two indices of speedup ratio and parallel efficiency in the communication model, asynchronous parallel algorithm is optimized, and the optimized system is applied to a diesel engine digital test system. Experimental result shows that not only the communication overhead problem in the process of data real-time transportation is solved, but also the data transmission efficiency of the distributed data acquisition system is improved effectively.
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Computer Engineering. 2013, 39(4): 280-282,286. https://doi.org/10.3969/j.issn.1000-3428.2013.04.064Common Cause Failure(CCF) makes the reliability analysis more complex. The Simulink simulation method of CCF reliability analysis based on Goal Orient(GO) methodology is put forward. The GO model of Common Cause Group(CCG) is presented with importing CCF. The cumulative probability algorithm is used for quantification calculate. The simulink model of CCG is presented for making modeling and calculating easier. An example shows that the improved method is more simple than the traditional calculation methods. Simulink has feasibility and validity in reliability GO analysis method of CCF .
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Computer Engineering. 2013, 39(4): 283-286. https://doi.org/10.3969/j.issn.1000-3428.2013.04.065The limitation of energy in battery powered devices is very challenging to apply H.264 to design a mobile sign language communication system. This paper therefore proposes a multiple priority Region of Interest(ROI) H.264 computation resource allocation scheme. In the system, the face, hands and background of sign language video is first detected with a fast algorithm. Then several coding parameters which allow the encoder to allocate computational resources differently are adaptively adjusted at the Macroblock(MB) level according to the relative priority of each MB. As a result, it keeps fine quality in face and hands, greatly reduces the computational complexity and prolongs the battery life.
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Computer Engineering. 2013, 39(4): 287-290,295. https://doi.org/10.3969/j.issn.1000-3428.2013.04.066When using Cholesky decomposition to solve large-scale linear equations system based on Field Programmable Gate Array(FPGA), the storage size limits and access bandwidth becomes its bottleneck. This paper proposes a solution based on hierarchical storage strategy and multi-ports block access method. The hierarchical storage structure is constituted with internal Bipolar Random Access Memory(BRAM) and external Synchronous Dynamic Random Access Memory(SDRAM). The internal BRAMs are mostly reused to further decrease the storage limits. Accessing external storage through multi-port and block data access methods enhances the effective bandwidth utilization and avoids the random access delay. Experimental results show that, the design can realize 17 to 215 times efficiency speedup compared with Xeon CPU.
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Computer Engineering. 2013, 39(4): 291-295. https://doi.org/10.3969/j.issn.1000-3428.2013.04.067To improve the speed of motion estimation, a fast integer pixel search algorithm for H.264 called Multi-level Cross Diamond Search(MCDS) algorithm is proposed. The algorithm uses the spatial correlation of Sum of Absolute Difference(SAD) value to set thresholds adaptively. It uses the spatial-temporal correlations of the motion vector field to predict the initial search points. And it makes early-termination judgment and selects search templates adaptively according to the relationship of the current minimum cost and the thresholds. It locates multi-cross diamond template precisely adopting the technologies of early-termination judgment and adaptive search templates selection. Experimental results show that the proposed algorithm can save a lot of motion estimation time while maintaining the search accuracy basically compared with the current algorithms.
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Computer Engineering. 2013, 39(4): 296-299,304. https://doi.org/10.3969/j.issn.1000-3428.2013.04.068A list intersection algorithm on Multi-Core CPU/GPU platform is put forward. For CPU, inwards intersection algorithm and refined Baeza-Yates algorithm are proposed, by taking advantage of data locality and in-order intersection strategy. they gain 0.79 and 1.25 times speed up respectively. For GPU, effective search interval thought is proposed. The search range is reduced by computing effective search interval in other lists of each Block, thus enhance the speed of the intersection, which improves the speed of list intersection by 40%. For mixed-platform, the operation of data preprocessing and I/O is hidden by time hiding technology, and the final system has a speed up of about 85%.
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Computer Engineering. 2013, 39(4): 300-304. https://doi.org/10.3969/j.issn.1000-3428.2013.04.069The existing Tibetan syntax system is complex, which is not conducive to the application of Tibetan natural language processing. So this paper describes an approach based on discriminant for analysis of Tibetan text dependency structure, where perceptron training method is used to training parsing model. And it also proposes a maximum spanning tree with CYK from the bottom-up algorithm for decoding. Experimental results show that, the method obtains acceptable score of 81.2% on manual test set. And it is applicable to Tibetan dependency library and other natural language processing.
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Computer Engineering. 2013, 39(4): 305-308. https://doi.org/10.3969/j.issn.1000-3428.2013.04.070Utilizing the finiteness of the uniform type number, this paper presents faster linear time algorithms for the Uniform Exchange(UE) problem and the Barter Uniform Exchange(BUE) problem. BUE is Transfered into a vertex constraint integer value maximum circulation problem on a constant order digraph, and the integrality of the feasible region of BUE’s integer linear programming formulation is proved. It is demonstrated that any optimal solution to BUE must be a subgraph of some optimal solution to the corresponding UE, and experimental results show that the two problems share a same asymptotical optimal values.
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Computer Engineering. 2013, 39(4): 309-313. https://doi.org/10.3969/j.issn.1000-3428.2013.04.071Focusing on the disadvantages of the binary search algorithm such as much query search times, large amount of data transfer and recognition for a long time, an multi-state binary anti-collision algorithm based on counting mechanism is developed. By utilizing the obtained collision information collected form preprocessing, the supreme conflict counting mechanism is introduced into the multi-state binary search algorithm. Experimental results show that the proposed algorithm can greatly reduce the query search times, the length of reader’s send command and tag’s response command as well as the identification time of recognition on tags in read range of the reader, combined with the traditional binary anti-collision algorithms.
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Computer Engineering. 2013, 39(4): 314-317. https://doi.org/10.3969/j.issn.1000-3428.2013.04.072Aiming at long encoding time of H.264/AVC video encoding serial algorithm, a new parallel algorithm based on dynamic scheduling strategy is proposed. The algorithm takes Group of Picture(GOP) as parallel encoding units and uses Master-Worker mode for communication with each other, reducing the communication costs of parallel encoding. Experimental results demonstrate its effectiveness and superiority of the algorithm in video encoding application, ensuring the quality of the video, getting high speedup. The algorithm has the ability to adapt to various status of node easily.
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Computer Engineering. 2013, 39(4): 318-320. https://doi.org/10.3969/j.issn.1000-3428.2013.04.073Spatial reference is lack for the calibration of the laser plane in three-dimensional measurement based on hand-hold light sectioning method. This paper proposes a laser plane calibration method based on precise movement. A checkerboard calibration target is adopted as spatial reference. Laser is projected on the checkerboard. The position of two straight-lines on the laser plane in the camera coordinate system is solved through the movement of checkerboard driven by milling. The position of the laser plane is determined by the amendment method for the straight lines of different surface. Experimental results confirm that the proposed method has good performance on accuracy and robustness.
2024
Volume 50 No 3
Volume 50 No 3
(Started in 1975, Monthly)
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428
Sponsored by：
East-China Institute of Computer Technology Shanghai Computer Society
Edited & Published by：
Editorial Board of Computer Engineering
Chief Editor：Jiang Bo
Executive Chief Editor:
Hu Bing
Tel：021-67092217
E-mail: ecice06@ecict.com.cn
CN: 31-1289/TP
ISSN: 1000-3428